Magnetic coupling device with at least one of a sensor arrangement and a degauss capability

ABSTRACT

Magnetic coupling devices are disclosed having magnetic field sensors. The magnetic coupling device may include degaussing coils wrapped about pole extension shoes of the magnetic coupling device.

RELATED APPLICATIONS

The present application claims the benefit of US Provisional PatentApplication No. 62/490,705, titled MAGNETIC COUPLING TOOL WITH SENSORARRANGEMENT, filed Apr. 27, 2017 and US Provisional Patent ApplicationNo. 62/490,706, titled MAGNETIC COUPLING TOOL WITH DEGAUSS CAPABILITY,filed Apr. 27, 2017, the entire disclosures of which are expresslyincorporated by reference herein.

TECHNICAL FIELD

The present disclosure is related to magnetic coupling devices having atleast one sensor to determine one or more parameters indicative of thequality of the magnetic circuit between the magnetic coupling device anda ferromagnetic workpiece, as well as, a relative position betweenmagnetic coupling device and the ferromagnetic workpiece. Additionally,the magnetic coupling devices may include degauss capability.

BACKGROUND

There are numerous devices which use magnetic fields in order to attractand or secure a ferromagnetic target to a working face of the device.Examples include magnetic clamping devices such as workplace chucks,permanent magnet lifting devices, magnetic latches, magnetic toolstands, etc.

Generally speaking, most of such devices include one or more sources ofmagnetic flux. These sources include electromagnets, electro-permanentmagnets, switchable permanent magnet units or arrangements, andcombinations thereof. In order to channel the magnetic flux provided bythe magnet(s) to one or more working face(s) of the device at which thetarget is to be secured magnetically, high magnetic permeability poleshoe or guides are often used, in creating a magnetic working circuit.

In many applications, and from a practical engineering perspective,users of such devices are primarily interested in determining the actual(pull) for which is exerted at the working face on the target, havingotherwise access to rating data of the magnet(s) employed in the deviceand which, all other aspects of the device-internal part of the magneticworking circuit being ideal, includes the Gauss rating of the magnet.The Gauss rating in turn allows determining of a maximum theoreticalpull force which such magnet(s) can exert on a target, using establishedformulae, where the target's size, geometry and ferromagneticcomposition enables it to be fully magnetically saturated. That is, itis assumed that no or only negligible stray magnetic field lines outsidethe circuit comprised of magnet, pole shoes and target exist, inparticular at the working face where ‘air gaps’ are often presentbetween pole shoes and target which adversely affect pull force. Somemagnet manufacturers also provide maximum pull force rating values fortheir magnets, based on laboratory testing.

It is well known tat the actual pull force exerted by a magnetic deviceon a target will be different to that determinable from the Gauss ratingof the magnet or the rated maximum pull force determined byexperimentation. The actual or effective pull force is reduced by anumber of factors, including uneven contact at the interface poleshoe—target (i.e. presence of air gaps at the interface), the interfacepole shop—target not being perpendicular to the magnetic field lines atthe interface, target having ‘thin’ dimensions leading to magnetic fieldlines extending past and outside the target (stray and leakage fluxleakage), target surface geometry and coatings, etc.

In the context or magnetic devices which use robotic arms and otherpositioning devices to move the device between off-target and on-targetoperating positions, additional factors beyond pull force need to beaccounted for, e.g. the need for precise positioning of the device withits working face against specific areas or zones on the target, whichcan be of as simple geometric shape as a plate or thin sheet metalstamping, to more complex multi-curved forms such as engine cam shafts.

Because many of these variables are difficult or impossible to predictin use of such magnetic devices, various operating methods and measuringsystems have been proposed and integrated into such magnetic devices, togain in-use and real-time information about qualitative and quantitativeparameters relevant to the external part of magnetic working circuit,relevantly whether the target is and remains safely attached to theworking face of the device, and whether the pull force remains withinsafety or rating thresholds.

Magnetic grippers are a common tool for handling steel workpieces inindustrial automation. They achieve large holding forces and arerelatively straight-forward to integrate into a robotics system, but forspecific problems noted below. Many magnetic grippers used in industryare cowered by pneumatic actuators. This prevents most magnetic grippersfrom interfacing with control electronics of a fully automated process.Without an interface between a magnet gripper and the controlelectronics, the robot (and the operator) has no easy way of obtainingfeedback from the magnet gripper on tool status or workpiece handlingperformance.

One common way around this in industry is to provide additional sensorson the outside of the magnet gripper to detect various tool states, suchas when the tool is turned fully on vs fully off, or when a target partis in contact with the magnet grippers working face. Though this methodof adding sensors works, it is expensive to add many additional andfunction-dedicated sensors. In addition, sensors added to the outside ofthe tool are vulnerable to damage from the robot's movement, operation,and surrounding environment. Additional sensors also add wiringcomplexity, making integration of the robot arm more expensive anddifficult.

Regardless of the lay-out and the interface between the magneticcoupling device and the workpiece, it is well known that ferromagneticworkpieces that have been exposed to a magnetic field during handling bysuch devices retain residual magnetism from the handling operation, inparticular where a strong magnetic field was used to generate sufficientpull force to retain the workpiece secured to the device. Relevantly,many cases it is desired for such workpieces to be totally or to aviable extent free of residual magnetism, for example where followingmagnetic handling a workpiece is to be machined or residual magnetismmay interfere with subsequent use of the workpiece.

It is equally well known that workpieces can be demagnetized by exposingthese to an alternating magnetic field of decreasing intensity, forexample by passing them through a field of an AC-powered DegaussingChamber (or coil) if they are small enough or moving a tool comprising ademagnetization coils over the part while generating an alternatingmagnetic field of decreasing intensity that ultimately removes theremaining magnetism from the workpiece.

One problem with such methodologies is that they require a separate,dedicated extra processing step in workpiece handling/machining routinesand/or a separate (additional) tool/device to perform the operation.

Against the above background, and in particular having regard to theadded challenges which integration of sensors into robotic end of arm(EOA) magnetic coupling tools such as grippers and workpiece transferequipment present, it is desired to provide a device (or tool) which isintended to allow integration of feedback measures in a magneticcoupling tool, to allow for superior operation and use of magnetictechnology in robotics. Exemplary feedback measures may include anindication of whether a target a workpiece) is properly magneticallyretained at the working face of the tool, an indication of a quality ofcoupling between an end-of-arm magnetic tool (EOAMT) and workpiece, suchas correct positioning of the tool within predetermined thresholds at atarget zone of the workpiece, detection of proximity of a targetworkpiece vis a vis EOAMT, and other factors. Further, it is desired toprovide magnetic coupling tools with improved degaussing functionality.

SUMMARY

Embodiments of the present disclosure relate to magnetic couplers forlifting, transporting, and/or holding a ferromagnetic workpiece.

In an exemplary embodiment of the present disclosure, a magneticcoupling tool for magnetically coupling to a ferromagnetic workpiece isprovided. The magnetic coupling tool comprising a housing and aswitchable magnetic flux source supported by the housing including aplurality of permanent magnets. The plurality of permanent magnetsincluding a first permanent magnet and a second permanent magnet movablerelative to the first permanent magnet. The magnetic coupling toolfurther comprising a plurality of workpiece engagement surfacessupported by the housing and magnetically coupled to the switchablemagnetic flux source. The plurality of workpiece engagement surfacesadapted to contact the ferromagnetic workpiece. A first workpieceengagement surface of the plurality of workplace engagement surfacescorresponding to a north pole of the magnetic coupling tool and a secondworkpiece engagement surface of the plurality of workpiece engagementsurfaces corresponding to a south pole of the magnetic coupling tool.The magnetic coupling toot further comprising a plurality of magneticfield sensors supported by the housing. A first magnetic field sensor ofthe plurality of magnetic field sensors positioned to monitor a firstmagnetic flux associated with the first workpiece engagement surface ofthe plurality of workpiece engagement surfaces and a second magneticfield sensor of the plurality of magnetic field sensors positioned tomonitor a second magnetic flux associated with the second workpieceengagement surface of the plurality of workpiece engagement surfaces.The magnetic coupling tool further comprising a logic control circuitoperatively coupled to the plurality of magnetic field sensors. Thelogic control circuit configured to determine at least one operatingstate of the magnetic coupling tool based on an output from at least oneof the plurality of magnetic field sensors.

In an example thereof, the logic control circuit is configured todetermine if the switchable magnetic flux source is in an off state. Ina variation thereof, the logic control circuit determines if theswitchable magnetic flux source is in an off state by a comparison of anoutput of at least one of the plurality of magnetic field sensors to afirst threshold stored on a memory accessible by the logic controlcircuit.

In another example thereof, the logic control circuit is configured todetermine if at least one of the plurality of workpiece engagementsurfaces is proximate to the ferromagnetic workpiece. In a variationthereof, the logic control circuit determines if at least one of theplurality of workpiece engagement surfaces is proximate to theferromagnetic workpiece by a comparison of an output of at least one ofthe plurality of magnetic field sensors to a second threshold stored ona memory accessible by the logic control circuit.

in a further example thereof, the logic control circuit is configured todetermine a spacing of the first workpiece engagement surface from theferromagnetic workpiece. In a variation thereof, the spacing of thefirst workpiece engagement surface from the ferromagnetic workpiece isdetermined by a comparison of an output of the first magnetic fieldsensor to at least one threshold stored on a memory accessible by thelogic control circuit.

In still another example thereof, the logic control circuit isconfigured to determine an orientation of the first workpiece engagementsurface and the second workpiece engagement surface relative to theferromagnetic workpiece. In a variation thereof, the orientation of thefirst workpiece engagement surface and the second workplace engagementsurface relative to the ferromagnetic workpiece is determined by acomparison of an output of the first magnetic field sensor and an outputof the second magnetic field sensor. In a further variation thereof, afirst spacing between the first workpiece engagement surface and theferromagnetic workpiece and a second spacing between the secondworkpiece engagement surface and the ferromagnetic workpiece aredetermined by the logic control circuit to be generally equal when theoutput of the first magnetic field sensor and the output of the secondmagnetic field sensor satisfy a first criteria in still a furthervariation thereof, the first criteria is that the output of the firstmagnetic field sensor is within a threshold amount of the output of thesecond magnetic field sensor.

In yet anther example, the logic control circuit is configured todetermine if a placement of the first workpiece engagement surface andthe second workpiece engagement surface relative to the ferromagneticworkpiece are within a target zone of the ferromagnetic workpiece. In avariation thereof, the placement of the first workpiece engagementsurface and the second workpiece engagement surface relative to theferromagnetic workpiece are determined to be within a target zone of theferromagnetic workpiece when both an output of the first magnetic fieldsensor satisfies a first criteria and an output of the second magneticfield sensor satisfies a second criteria. In a further variationthereof, the first criteria is the output of the first magnetic fieldsensor is within a first range of magnetic flux values and the secondcriteria is the output of the second magnetic field sensor is within asecond range of magnetic flux values. In a still further venationthereof, the first range of magnetic flux values includes a first limitvalue corresponding to the first workpiece engagement surface positionedat a first limit position of the target zone relative to theferromagnetic workpiece and a second limit value corresponding to thefirst workpiece engagement surface positioned at a second limit positionof the target zone relative to the ferromagnetic workpiece. In yet stilla further variation thereof, the second range of magnetic flux valuesincludes a first limit value corresponding to the second workpieceengagement surface positioned at a first limit position of the targetzone relative to the ferromagnetic workpiece and a second limit valuecorresponding to the second workpiece engagement surface positioned at asecond limit position of the target zone relative to the ferromagneticworkpiece. In yet another still variation, the logic control circuitdetermines a first end of the magnetic coupling toot including the firstworkpiece contact surface is positioned outside of the target zone whenthe second criteria is satisfied and the first criteria is notsatisfied. In a further yet variation, the logic control circuitdetermines a second end of the magnetic coupling tool including thesecond workpiece contact surface is positioned outside of the targetzone when the first criteria is satisfied and the second criteria is notsatisfied.

In still yet another example, the logic control circuit is configured todetermine an orientation of the first workpiece engagement surface andthe second workpiece engagement surface relative to the ferromagneticworkpiece in two rotational axes based on the output of the plurality ofmagnetic field sensors. In a variation thereof, the plurality ofmagnetic field sensors includes a third magnetic field sensor and afourth magnetic field sensor. The first magnetic field sensor beingpositioned in a left side half of the magnetic coupling tool. The secondmagnetic field sensor being positioned in a right side half of themagnetic coupling tool. The third magnetic field sensor being positionedin a front half of the magnetic coupling tool, the front half includinga first portion of the left side half and a first portion of the rightside half. The fourth magnetic field sensor being positioned in a rearhalf of the magnetic coupling tool, the rear half including a secondportion of the left side half and a second portion of the right sidehalf. The logic control circuit determines the orientation of the firstworkplace engagement surface and the second workplace engagement surfacerelative, to the ferromagnetic workplace in two rotational axes based onthe output of each of the first magnetic field sensor, the secondmagnetic field sensor, the third magnetic field sensor, and the fourthmagnetic field sensor. In another variation thereof, the logic controlcircuit is configured to determine an orientation of the first workplaceengagement surface and the second workpiece engagement surface relativeto the ferromagnetic workpiece in two rotational axes based on theoutput of the plurality of magnetic field sensors, the first magneticfield sensor and the second magnetic field sensor each being athree-dimensional magnetic field sensor. In still another variationthereof, the logic control circuit is further configured to determine aspacing of the magnetic coupling tool relative to the ferromagneticworkpiece. In a further still variation, the logic control circuit isconfigured to determine the spacing of the magnetic coupling toolrelative to the ferromagnetic workpiece independent of the orientationof the magnetic coupling tool relative to the ferromagnetic workplace.

In a further yet example, the logic control circuit is configured todetermine, whether one or more of the workplace engagement surfaces atthe pole extension shoes abut a workpiece, and whether abutment of aworkplace at one or more of the workpiece engagement surfaces isadequate and within predetermined positional thresholds.

In another still example, the magnetic coupling tool further comprisesan actuator operatively coupled to the second permanent magnet to movethe second permanent magnet relative to the first permanent magnet. In avariation thereof, the actuator is a stepper motor. In another variationthereof, the logic control circuit is operatively coupled to theactuator to control an orientation of the second permanent magnetrelative to the first permanent magnet.

In yet another example thereof, the second permanent magnet is rotatablerelative to the first permanent magnet about an axis intersecting withthe second permanent magnet to alter a position of the second permanentmagnet relative to the first permanent magnet.

In still yet another example thereof, the second permanent magnet isrotatable relative to the first permanent magnet about an axis in anon-intersecting relationship with the second permanent magnet to altera position of the second permanent magnet relative to the firstpermanent magnet. In a variation thereof, the magnetic coupling toolfurther comprises a first platter supported by the housing and a secondplatter supported by housing. The second platter being moveable relativeto the first platter to alter a position of the second permanent magnetrelative to the first permanent magnet. The first platter comprising afirst plurality of spaced apart permanent magnets including the firstpermanent magnet, each of the first plurality of spaced apart permanentmagnets has a north pole side and a south pole side, and a firstplurality of pole portions interposed between adjacent permanent magnetsof the first plurality of permanent magnets, wherein the first pluralityof permanent magnets are arranged so that each pole portion of the firstplurality of pole portions is one of a north pole portion which isadjacent the north pole side of two permanent magnets of the firstplurality of permanent magnets and a south pole portion which isadjacent the south pole side of two permanent magnets of the firstplurality of permanent magnets. The second platter comprising a secondplurality of spaced apart permanent magnets including the secondpermanent magnet, each of the second plurality of spaced apart permanentmagnets has a north pole side and a south pole side, and a secondplurality of pole portions interposed between adjacent permanent magnetsof the second plurality of permanent magnets, wherein the secondplurality of permanent magnets are arranged so that each pole portion ofthe first plurality of pole portions is one of a north pole portionwhich is adjacent the north pole side of two permanent magnets of thesecond plurality of permanent magnets and a south pole portion which isadjacent the south pole side of two permanent magnets of the secondplurality of permanent magnets, wherein the first magnetic sensor isassociated with one of the north pole portions of the second platter andthe second magnetic sensor is associated with one of the south poleportions of the second platter.

In another still example thereof, the magnetic coupling tool furthercomprises a plurality of pole extension shoes supported by the housing.The plurality of pole extension shoes including a first pole extensionshoe including the first workpiece engagement surface and a second poleextension shoe including the second workpiece engagement, wherein thehousing includes a lower side positioned between the first poleextension shoe and the second pole extension shoe, the first poleextension shoe and the second pole extension shoe extending below thelower side of the housing. In a variation thereof, the first poleextension shoe and the second ode extension shoe are removable from thehousing.

In a further still example thereof, the first magnetic field sensor andthe second magnetic field sensor ere positioned outside of an envelopeof the second permanent magnet.

In another example thereof, the first magnetic field sensor ispositioned in a first half of the magnetic coupling tool and the secondmagnetic field sensor is positioned in a second half of the magneticcoupling tool. In a variation thereof, the first pole extension shoe isassociated with a flux detection circuit surface opposite the workpieceengagement surface of the first pole extension shoe the first magneticsensor is positioned above the flux detection circuit associated withthe first pole extension shoe. In another variation thereof, the housingincludes a first recess, the first pole extension shoe being received inthe first recess and the first magnetic sensor being positioned directlyabove the first recess. In another variation thereof, the second poleextension shoe is associated with a flux detection circuit surfaceopposite the workpiece engagement surface of the second pole extensionshoe, the second magnetic sensor is positioned above the flux, detectioncircuit associated with the second pole extension shoe. In a furthervariation thereof, the housing includes a second recess, the second poleextension shoe being received in the second recess and the secondmagnetic sensor being positioned directly above the second recess.

In a further example thereof, the first magnetic field sensor and thesecond magnetic field sensor are positioned within the housing.

In a further still example thereof, the magnetic coupling tool furthercomprises at least one temperature sensor supported by the housing, thelogic control circuit is operatively coupled to the at least onetemperature sensor and the logic control circuit based on, an output ofthe temperature sensor adjusts the output received from the at least oneof the plurality of magnetic field sensors.

In still a further example thereof, the first magnetic field sensor andthe second magnetic field sensor are each vector magnetometers.

In yet an example thereof, the magnetic coupling tool further comprisesa communication module supported by the housing, wherein the logiccontrol circuit is operatively coupled to the communication module tointerface with external control electronics.

In another example thereof, the magnetic coupling tool further comprisesa plurality of degaussing electrical windings. A first degaussingelectrical winding of the plurality of degaussing electrical windingsbeing positioned about the first pole extension shoe of the plurality ofpole extension shoes. A second degaussing electrical winding of theplurality of degaussing electrical windings being positioned about asecond pole extension shoe of the plurality of pole extension shoes. Thelogic control circuit is operatively coupled to the first degaussingelectrical winding and the second degaussing electrical winding. Thelogic control circuit configured to perform a degaussing cycle with theplurality of degaussing electrical windings. The degaussing cycleincluding generating an oscillating and alternating magnetic field withthe first degaussing electrical winding and the second degaussingelectrical winding for a period of time. In a variation thereof, each ofthe first pole extension shoe and the second pole extension shoe includea first portion covered by the respective first and second degaussingelectrical windings, a cross sectional area of the respective firstportions being sufficient to direct a substantial and preferably all ofthe magnetic flux generated upon the respective first and seconddegaussing electrical windings being energised to the respective firstand second workpiece engagement surfaces. In another variation thereof,the first workpiece engagement surface and the second workpieceengagement surface are both in contact with the ferromagnetic workpieceduring the degaussing cycle and the switchable magnetic flux source isin an off state.

In still another example thereof, the magnetic coupling device furthercomprises an output device which provides an indication of the operatingstate the magnetic coupling device.

In a further example thereof, the magnetic coupling device furthercomprises an output device which provides a plurality of distinctindications, each corresponding to a respective one of a plurality ofdistinct operating states of the magnetic coupling device. In avariation thereof, the plurality of distinct indications are each avisual indication perceivable from an exterior of the housing. Inanother variation thereof, the output device includes a plurality oflights which are controlled to provide the plurality of distinctindications.

In another exemplar y embodiment of the present disclosure, a roboticsystem for lifting a ferromagnetic workpiece is provided. The roboticsystem comprising a robotic arm including a base and a plurality ofmoveable arm segments and a magnetic coupling device according to anyone of the above mentioned embodiments, examples, and variations, themagnetic coupling device being operatively coupled to the robotic arm ata first end opposite the base.

In a further exemplary embodiment of the present disclosure, a method ofdetermining at least one operating state of a magnetic coupling tool isprovided. The method comprising the steps of: detecting a first magneticflux associated with a north pole of a switchable magnetic flux sourcesupported by a housing, the switchable magnetic flux source including aplurality of permanent magnets, including a first permanent magnet and asecond permanent magnet movable relative to the first permanent magnet,the first magnetic flux being detected at a location remote from aworkplace engagement surface of the north pole of the magnetic couplingtool and to a first side of the switchable magnetic flux source;detecting a second magnetic flux .associated with a south pole of theswitchable magnetic flux source, the second magnetic flux being detectedat a location remote from a workpiece engagement surface of the southpole of the magnetic coupling tool and to a second side of theswitchable magnetic flux source, the second side being opposite thefirst side; and determining if the magnetic coupling tool is in a firstoperating state based on at least one of the detected first magneticflux and the detected second magnetic flux.

In an example thereof, the step of determining the first operating stateof the magnetic coupling tool includes the steps of determining if thedetected first magnetic flux satisfies a first criteria; determining ifthe detected second magnetic flux satisfies a second criteria; anddetermining that the magnetic coupling tool is in the first operatingstate if the detected first magnetic flux satisfies the first criteriaand the detected second magnetic flux satisfies the second criteria. Ina variation thereof, the first criteria is the output of the firstmagnetic field sensor is within a first range of magnetic flux valuesand the second criteria is the output of the second magnetic fieldsensor is within a second range of magnetic flux values. In a furthervariation thereof, the first range of magnetic flux values includes afirst limit value corresponding to the first workpiece engagementsurface positioned at a first limit position of a target zone relativeto the ferromagnetic workpiece and a second limit value corresponding tothe first workplace engagement surface positioned at a second limitposition of the target zone relative to the ferromagnetic workpiece. Ina still further variation thereof, the second range of magnetic fluxvalues includes a first limit value corresponding to the secondworkplace engagement surface positioned at a first limit position of thetarget zone relative to the ferromagnetic workplace and second limitvalue corresponding to the second workpiece engagement surfacepositioned at a second limit position of the target zone relative to theferromagnetic workpiece. In another variation, the method furthercomprises the step of determining the first side of the magneticcoupling tool including the first workpiece contact surface ispositioned outside of a target zone on the ferromagnetic workpiece whenthe second criteria is satisfied and the first criteria is notsatisfied. In another variation thereof, the method further comprisesthe step of determining the second side of the magnetic coupling toolincluding the second workpiece contact surface is positioned outside ofa target zone on the ferromagnetic workpiece when the first criteria issatisfied and the second criteria is not satisfied.

In another example thereof, the first operating state is the magneticcoupling tool is in an off state. In a variation thereof, the step ofdetermining if the magnetic coupling tool is in the first operatingstate includes the step of comparing of an output of at least one of theplurality of magnetic field sensors to a first threshold.

In yet another example, the first operating state is that at least oneof the plurality of workpiece engagement surfaces is proximate to theferromagnetic workpiece. In a variation thereof, the step of determiningif the magnetic coupling tool is in the first operating state includesthe step of comparing an output of at least one of the plurality ofmagnetic field sensors to a second threshold stored on a memoryaccessible by the logic control circuit.

In still another example thereof, the method further comprises the stepof determining a spacing of the first workpiece engagement surface fromthe ferromagnetic workpiece.

In still a further example thereof, the method further comprises thestep of determining an orientation of the first workpiece engagementsurface and the second workpiece engagement surface relative to theferromagnetic workpiece. In a variation thereof, the step of determiningthe orientation of the first workpiece engagement surface and the secondworkpiece engagement surface relative to the ferromagnetic workpieceincludes the step of comparing an output of the first magnetic fieldsensor and an output of the second magnetic field sensor. In anothervariation thereof, the first workpiece engagement surface and the secondworkpiece engagement surface of the magnetic coupling tool are generallyparallel to the ferromagnetic workpiece when the output of the firstmagnetic field sensor and the output of the second magnetic field sensorsatisfy a first criteria. In a still further variation thereof, thefirst criteria is that the output of the first magnetic field sensor iswithin a threshold amount of the output of the second magnetic fieldsensor.

In still a further exemplary embodiment of the present disclosure, amagnetic coupling tool for magnetically coupling to a ferromagneticworkplace is provided. The magnetic coupling tool comprising: a housing;a switchable magnetic flux source supported by the housing in aplurality of permanent magnets; the plurality of permanent magnetsincluding a first permanent magnet and a second permanent magnet movablerelative to the first permanent magnet; a plurality of pole extensionshoes each having a workpiece interface; the plurality of pole extensionshoes coupled to the housing to receive magnetic flux from theswitchable magnetic flux source, the received magnetic flux beingavailable to the ferromagnetic workpiece through the respectiveworkpiece interfaces of the plurality of pole extension shoes; aplurality of degaussing electrical windings, a first degaussingelectrical winding of the plurality of degaussing electrical windingsbeing positioned about a first pole extension shoe of the plurality ofpole extension shoes and a second degaussing electrical winding of theplurality of degaussing electrical windings being positioned about asecond pole extension shoe of the plurality of extension shoes; and alogic control circuit operatively coupled to the switchable magneticflux source. The first degaussing electrical winding, and the seconddegaussing electrical winding, the logic control circuit configured to(i) position the second permanent magnet in a first orientation relativeto first permanent magnet and (ii) perform a degaussing cycle with theplurality of degaussing electrical windings, the degaussing cycle ingenerating an oscillating and alternating magnetic field with the firstelectrical winding and the second electrical winding for a period oftime.

In an example thereof, each of the first pole extension shoe and thesecond pole extension shoe include a first portion covered by therespective first and second degaussing electrical windings, a crosssectional area of the respective first portions being sufficient todirect a substantial and preferably all of the magnetic flux generatedupon the respective first and second degaussing electrical windingsbeing energised to the respective first and second workpiece engagementsurfaces.

In another example thereof, the first workpiece engagement surface andthe second workpiece engagement surface are both in contact with theferromagnetic workpiece during the degaussing cycle and the switchablemagnetic flux source is in an off state.

In a further exemplary embodiment of the present disclosure, an end ofarm magnetic coupling tool (EOAMT) devised for magnetically securing, aferromagnetic workpiece to a working face of the tool is provided. Theend of arm magnetic coupling tool comprising: an on-off switchablemagnetic flux source; a housing component in which is received themagnetic flux source; at least two, magnetic pole extension shoes havingeach a workpiece engagement surface and flux detection surface at an endopposite to the workpiece engagement surface, wherein the pole extensionshoes are mounted to or at least partially form integral part of thehousing component such as to receive magnetic flux from the magneticflux source and make such available at the workpiece engagement surface;a number of first magnetic field detection sensors equal in number tothe pole extension shoes and each located a predetermined distance awaybut in close proximity to the flux detection surface of an associatedone of the pole extension shoes; and a logic control circuit operativeto receive an output signal from one or more of the magnetic fielddetection sensors and determine from said output signal(s) at least oneof the following operating states of the tool; whether the magnetic fluxsource is switched on or off, whether there is a ferromagnetic workpiecein spatial proximity to one or more of the workpiece engagement surfacesat the pole extension shoes, whether one or more of the workpieceengagement surfaces at the pole extension shoes abut a workpiece, andwhether abutment of a workpiece at one or more of the workpieceengagement surfaces is adequate and within predetermined positionalthresholds.

In an example thereof, the first magnetic field sensors and the logiccontrol circuit are housed within a further (second) housing componentwhich is preferably of multi-piece construction and which is secured tothe first housing component, such as to provide a compact-footprintEOAMT with integrated magnetic field detection and workpiece-toolinterface detection capabilities.

In another example thereof, the magnetic flux source, the first housingcomponent and the pole extension shoes are comprised in an on-oftswitchable, dipole permanent magnet unit. In a variation thereof, thefirst housing component is a ferromagnetic steel housing component witha central cylindrical bore in which two cylindrical, diametricallypolarized rare-earth permanent magnets are stacked such that one of themagnets is fixed against rotating within the cylindrical bore while theother magnet is free to rotate upon external torque application by anactuator (pneumatic, hydraulic or electric) interfaced with therotatable magnet. In another variation thereof, the housing componentcomprises an upper, un-recessed portion and a tower recessed portion atwhich cuboid pole shoes are mounted such as to form a continuous,substantially air-gap-free flux delivery path towards the workpieceengagement surfaces provided at the free axial terminal ends of the poleshoes, and wherein the flux detection surfaces opposite the workpieceengagement surfaces are provided at an upper terminal face of theun-recessed housing portion, the housing having a substantiallyrectangular foot print.

In a further example thereof, a second housing component is provided inaddition to the first housing component, secured to an end of the firsthousing component opposite the workpiece engagement surfaces. In avariation thereof, the second housing component is substantiallynon-ferromagnetic and includes at least two passage ways extendingpreferably to terminal openings located opposite the flux detectionsurfaces at the first housing component and receiving a respective oneof two said first magnetic field detection sensors. In another variationthereof, the second housing component houses an actuator whichinterfaces with the rotatable magnet received in the first housingcomponent to switch the magnetic flux source “on” and “off”.

in still a further variation, the logic control circuit operative toreceive output signals from the one or more of the first magnetic field(and any additional) detection sensors and determine from said outputsignal(s) one or more of the operating states of the tool, comprises acentral control board, preferably a printed circuit board which containsa pre-programmed or programmable microprocessor, with analog to digitalconverters (ADCs) for sensor signal sampling and optionally withconditioning functionality. In a variation thereof, the logic controlcircuit of the central control board comprises additional transistorsfor interfacing a GPIO (general-purpose input/output) of the processorto industrial 24V logic. In another variation thereof, the centralcontrol board further comprises power conditioning to take 24V from anindustrial power supply and regulate it to 5V and/or 3.3V for use by themicroprocessor and other circuit components, as well as provide theworking voltage for the magnetic field sensors. In still anothervariation thereof, the central control board comprises a series of blankheaders for accept a communications module that allows the control boardto interface with external control electronics.

In yet another example, the first magnetic field sensors are vectormagnetometers, in particular solid-state linear Hall Effect sensors ormagneto resistive sensors, with very small form factor and embodied insolid state ICs.

In still yet another example, the end of arm magnetic coupling toolfurther comprises visual status indicators, preferably in form of one ormore LEDs which are driven by the microprocessor to indicate when apredefined one of the tool status is present or absent, including whenthe magnetic flux source is on or off, when the magnetic flux source ison and proximity of target is detected by the first magnetic fieldsensors, when the tool's workpiece engagement surfaces contact theworkpiece outside intended specific areas on target and when toolengagement with the workpiece is within threshold limits, showing a safemagnetic coupling state.

In still a further exemplary embodiment thereof, an end of arm magneticcoupling tool devised for magnetically securing a ferromagneticworkpiece to a working face of the tool is provided. The end of armmagnetic coupling tool comprises: an on-off switchable di-pole magneticflux source; a first housing component in which is received the magneticflux source; a pair of magnetic pole extension shoes having each aworkpiece engagement surface, wherein the pole extension shoes aremounted to the first housing component such as to receive magnetic fluxfrom the magnetic flux source and make such available at the work pieceengagement surfaces: at least one, but preferably a number of firstmagnetic field detection sensors equal in number to the pole extensionshoes, located a predetermined distance away but in close proximity to aflux detection surface preferably at an end opposite the workpieceengagement surface of an associated one of the pole extension shoes; apair of degaussing electrical windings, one each wound about a sectionof an associated one of the two magnetic pole extension shoes; and alogic control circuit operative to (i) receive an output signal from theat least one magnetic field detection sensor and determine from saidoutput signal(s) an operating state of the tool indicative of themagnetic flux source being switched off, (ii) switch-on an electricpower supply to the degaussing electrical windings after detection of anoff state of the magnetic flux source and (iii) perform a degaussingcycle wherein the degaussing electrical windings generate an oscillatingand alternating magnetic field over a predetermined time.

In an example thereof, the first magnetic field sensors and the logiccontrol circuit are housed within a second housing component which ispreferably of multi-piece construction and which is secured to the firsthousing component such as to provide a compact-footprint EOAMT withintegrated workpiece coupling, magnetic field detection, workpiece-toolinterface detection and degaussing functionalities.

In another example thereof, the magnetic flux source, the first housingcomponent and the pole extension shoes are comprised in on-offswitchable, dipole permanent magnet unit.

In yet an other example, the first housing component is a ferromagneticsteel housing component with a central cylindrical bore in which twocylindrical, diametrically polarized rare-earth permanent magnets arestacked such that one of the magnets s fixed against rotation with inthe cylindrical bore while the other magnet is free to rotate uponexternal torque application by an actuator interfaced with the rotatablemagnet.

In still another example thereof, the pole extension shoes compose atleast two components, including a first pole extension member secured inremovable manner to the first housing component and a second poleextension member removably secured in extension to the first member anddefining the workpiece engagement surface. In a variation thereof, thedegaussing electrical windings encircle a section of the second poleextension member. In another variation thereof, the second pole shoemember has a workpiece engagement surface adapted to a contour orgeometric parameters of a workpiece.

In yet another example, the pole extension shoes have, in a sectioncovered by the degaussing windings, a cross sectional area sufficient todirect a substantial and preferably all of the magnetic flux generatedupon the degaussing windings being energised, to the workpieceengagement surface.

In still another example, the pole extension shoes have, in a sectioncovered by the degaussing windings, a cross sectional area sufficient todirect a substantial portion of the magnetic flux generated upon thedegaussing windings being energised, to the workpiece engagement surfaceand generate magnetic flux leakage around the workpiece engagementsurface.

In yet still another example, the first housing component comprises nupper, un-recessed portion and a lower portion recessed at oppositesides of the housing component, wherein the pole shoe extension membersare or comprise a cuboid mounted to the recessed lower housing portionssuch as to form with the upper, un-recessed housing portion acontinuous, substantially air-gap-free flux delivery path towards theworkpiece engagement surfaces provided at the free axial terminal endsof the pole extension shoes, and wherein the flux detection surfacesopposite the workpiece engagement surfaces are provided at an upperterminal face of the un-recessed housing portion. In a variationthereof, the first housing component comprises through holes for guidingconnection loads from the logic control circuit to the electricdegaussing windings.

In a further example thereof, the second housing component issubstantially non-ferromagnetic and preferably includes at least twopassage ways extending from the through holes of the first housingcomponent to the logic control circuit.

In yet a further example thereof, the logic control circuit is devisedto perform the degaussing cycle when the tool is still resting with itsworkpiece engagement surfaces at the workpiece after having beenmagnetically secured thereto and the magnetic flux source has beenturned off to effect decoupling from the workpiece. In a variationthereof, the logic, control circuit comprises a central control board,preferably a printed circuit board, which contains a pre-programmed orprogrammable microprocessor and circuitry for generating an AC signalcausing the degaussing windings to generate the oscillating andalternating magnetic degaussing field. In another variation thereof, thelogic control circuit, of the central control board comprises componentsfor interfacing a GPIO (general-purpose input/output) of the processorto industrial 24V logic. In still another venation thereof, the centralcontrol board further comprises power conditioning to take 24V from anindustrial power supply and regulate it to an operating value requiredby the electric degaussing windings to perform the degaussing cycle.

In a further still example, the end of arm magnet coupling tool furthercomprises visual status indicators, preferably in form of one or moreLEDs which are driven by the microprocessor to indicate when apredefined one of the tool status is present or absent, including whenthe magnetic flux source is on or off and when a degaussing cycle isbeing performed.

In a yet further example, the degaussing electrical windings andexchangeable pole extension shoe members form modular units attachableto the first housing component, wherein the pole extension shoe membersform part of a magnetic flux delivery circuit of the EOAMT when used inmagnetically coupling the EOAMT with a workpiece, and wherein the poleextension shoe members form part of an electromagnet comprising thedegaussing windings in degaussing the work piece.

Other aspects and optional and/or preferred embodiments will becomeapparent from the following description provided below with reference tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of an exemplary end-of-armmagnetic coupling tool;

FIG. 2 illustrates a side elevation of end-of-arm magnetic coupling toolof FIG. 1 ;

FIG. 3 illustrates an exploded perspective view of the end-of-armmagnetic coupling tool of FIG. 1 ;

FIG. 4 illustrates an exploded perspective view of an exemplaryswitchable permanent magnet unit, a magnetic flux source, andreplaceable pole extension shoes of the end-of-arm magnetic couplingtool of FIG. 1 ;

FIG. 5 illustrates an exploded perspective view of a second housingcomponent of the end-of-arm magnetic coupling tool of FIG. 1 whichhouses an exemplary actuator for switching of the magnetic flux source,a plurality of exemplary magnetic field sensors for interaction with thehousing and pole shoes of the magnetic flux source, and an exemplaryon-board logic control circuit for delivering tool status data andindication via an exemplary output device;

FIG. 6 illustrates a perspective view of portions of the logic controlcircuit of FIG. 5 including an exemplary coupled sensor printed circuitboard assembly and an exemplary control logic printed circuit board withan exemplary input/output connector;

FIG. 7 illustrates a side elevation of FIG. 6 ;

FIG. 8 illustrates a perspective view of an embodiment of the end-of-armmagnetic coupling tool of FIG. 1 including degauss capability;

FIG. 9 illustrates a side elevation view of the arrangement of FIG. 8 ;

FIG. 10 illustrates an exploded view of the magnetic flux source of theend-of-arm magnetic coupling tool of FIG. 8 , being an on/off switchablepermanent magnet unit, and two degaussing modules that carry poleextension shoes for the magnetic flux source;

FIG. 11 illustrates an exploded view of one of the degaussing modulesshown in FIG. 8 ;

FIG. 12 illustrates an exemplary degauss wave form of use in adegaussing cycle with the degaussing modules of FIG. 11 ;

FIG. 13 illustrates a representative view of the logic control circuitof the end-of-arm magnetic coupling tool of FIG. 1 ;

FIG. 14 illustrates a top view of an exemplary sensor layout of theend-of-arm magnetic coupling tool of FIG. 1 ;

FIG. 15 illustrates a simplified front elevation view of the end of armmagnetic coupling device of FIG. 1 and no workpiece in the proximity ofthe end of arm magnetic coupling device;

FIG. 16 illustrates a simplified front elevation view of the end of armmagnetic coupling device of FIG. 1 and a workpiece separated from theend of arm magnetic coupling device by a first separation;

FIG. 17 illustrates a simplified front elevation view of the end of armmagnetic coupling device of FIG. 1 and a workpiece separated from theend of arm magnetic coupling device by a second separation;

FIG. 18 illustrates a simplified front elevation view of the end of armmagnetic coupling device of FIG. 1 being tilted left-to-tight relativeto a workplace;

FIG. 19 illustrates a simplified front elevation view of the end of armmagnetic coupling device of FIG. 1 being tilted front-to-back relativeto a workpiece;

FIG. 20 illustrates a simplified front elevation view of the end of armmagnetic coupling device of FIG. 1 contacting a right edge portion of aworkplace;

FIG. 21 illustrates a simplified front elevation view of the end of armmagnetic coupling device of FIG. 1 contacting a central portion of aworkplace;

FIG. 22 illustrates a simplified front elevation view of the end of armmagnetic coupling device of FIG. 1 contacting a workplace at a firstlimit position;

FIG. 23 illustrates a simplified front elevation view of the end of armmagnetic coupling device of FIG. 1 contacting a workpiece at a secondlimit position;

FIG. 24 illustrates an exemplary processing sequence of the controllogic, including calibration subroutine, performed by the end-of-armmagnetic coupling tool during operation;

FIG. 25 illustrates a robotic system including the exemplary magneticcoupling device of FIG. 1 attached as an end of arm coupler;

FIG. 26 illustrates an exploded perspective view of an exemplary platterhaving a plurality of permanent magnets and pole portions;

FIG. 27 illustrates a top, assembled view of the platter of FIG. 26 ;

FIG. 28 illustrates a perspective view of the two instances of theplatter of FIG. 26 ;

FIG. 29 illustrates the two platters of FIG. 28 oriented in an on state;

FIG. 30 illustrates the two platter of FIG. 28 oriented in an off state;

FIG. 31 illustrates a diagrammatical view of an exemplary magneticcoupling device having an upper assembly and a lower assembly, eachincluding a plurality of permanent magnets and pole portions arranged ina linear array, the magnetic coupling device being in an on state;

FIG. 32 illustrates the magnetic coupling device of FIG. 31 in a partialon state;

FIG. 33 illustrates the magnetic coupling device of FIG. 31 in an offstate;

FIG. 34 illustrates a perspective view of an exemplary linear arraymagnetic coupling device including sensors and logic control circuit fordetermining operational states of the magnetic coupling device;

FIG. 35 illustrates a bottom view of the linear array magnetic couplingdevice of FIG. 34 ;

FIG. 36 illustrates a perspective view of an exemplary circular arraymagnetic coupling device including sensors and logic control circuit fordetermining operational states of the magnetic coupling device; and

FIG. 37 illustrates a bottom view of the circular magnetic couplingdevice of FIG. 36 .

DETAILED DESCRIPTION OF THE DRAWINGS

In the figures as well as in the preceding section of thisspecification, terms such as ‘upper’, ‘lower’, ‘axial’ and other termsof reference are used to facilitate an understanding of the technologyhere described and are not to be taken as absolute and limitingreference indicators, unless the context indicates otherwise. The terms“couples”, “coupled”, “coupler” and variations thereof are used toinclude both arrangements wherein the two or more components are indirect physical contact and arrangements wherein the two or morecomponents are not in direct contact with each other (e.g., thecomponents are “coupled” via at least a third component), but yet stillcooperate or interact with each other.

Referring to FIG. 1 , an exemplary magnetic coupling tool 10 is shown.Magnetic coupling tool 10 is configured to magnetically couple aferromagnetic workpiece 17 (see FIG. 21 ). Magnetic coupling tool 10 isdescribed herein for use as an end of arm (“EOAMT”) unit for a roboticsystem, such as robotic system 700 (see FIG. 25 ) but may also used withother lifting and transporting systems for ferromagnetic materials.Exemplary lifting and transporting systems include robotic systems,mechanical gantries, crane hoists and additional systems which liftand/or transport ferromagnetic materials. Additionally, magneticcoupling tool 10 may also be used as part of a stationary fixture forholding at least one part for an operation, such as welding, inspection,and other operations. Logic control circuit 23 by monitoring sensors 98is able to verify that the part being held on the stationary fixture isin a correct position.

Referring to FIGS. 1-3 , magnetic coupling tool 10 includes a housing 11and a switchable magnetic flux source 15 (see FIG. 3 ) supported byhousing 11. The switchable magnetic flux source 15 includes a pluralityof permanent magnets, illustratively- permanent magnets 30, 32 (see FIG.3 ). The plurality of permanent magnets in a first permanent magnet 30and a second permanent magnet 32 movable relative to the first permanentmagnet 30. First permanent magnet 30 being held fixed relative tohousing 11. Magnetic coupling tool 10 further including a plurality ofworkpiece engagement surfaces 44 supported by housing 11. The pluralityof workpiece engagement surfaces 44 being magnetically coupled toswitchable magnetic flux source 15. The plurality of workpieceengagement surfaces 44 adapted to contact the ferromagnetic workpiece 17(see FIG. 21 ). A first workpiece engagement surface 44 of the pluralityof workpiece engagement surfaces corresponding to a north pole of themagnetic coupling tool 10 and a second workpiece engagement surface 44of the plurality of workpiece engagement surfaces corresponding to asouth pole of the magnetic coupling tool 10.

Magnetic coupling tool 10 further includes a plurality of magnetic fieldsensors 98 (see FIG. 3 ) supported by housing 11. A first magnetic fieldsensor 98 of the plurality of magnetic field sensors positioned tomonitor a first magnetic flux associated with the first workpieceengagement surface 44 of the plurality of workpiece engagement surfacesand a second magnetic field sensor 98 of the plurality of magnetic fieldsensors positioned to monitor a second magnetic flux associated with thesecond workpiece engagement surface 44 of the plurality of workpieceengagement surfaces. Magnetic coupling device 10 further including alogic control circuit 23 operatively coupled to the plurality ofmagnetic field sensors 98. Logic control circuit 23 is configured todetermine at least one operating state of magnetic coupling tool 10based on an output from at least one of the plurality of magnetic fieldsensors 98.

In the illustrated embodiment of FIGS. 1-11 , magnetic coupling device10 is an end of arm magnetic coupling tool (herein “EOAMT”) devised formagnetically securing a ferromagnetic workpiece 17 to a working face 44of the tool 10. The end of arm magnetic coupling tool 10 comprises anon-off switchable magnetic flux source 15; a first housing component 22of housing 11 in which is received the magnetic flux source 15; and atleast two, magnetic pole extension shoes 38 each having each a workpieceengagement surface 44 and a flux detection surface 46 at an end oppositeto the workpiece engagement surface 44. Pole extension shoes 38 aremounted to or at least partially form integral part of the first housingcomponent 22 such as to receive magnetic flux from the magnetic fluxsource 16 and to make such received magnetic flux available at theworkpiece engagement surfaces 44. In embodiments, workpiece engagementsurfaces 44 are part of housing 22. Tool 10 further includes a number ofmagnetic field detection sensors 98. In embodiments, the number ofmagnetic field detection sensors is equal in number to the number ofpole extension shoes 38 and/or workpiece engagement surfaces 44. Each ofthe magnetic field detection sensors 98 is located a predetermineddistance away, but in close proximity to the flux detection surface ofan associated one of the pole extension shoes 38. In one example, themagnetic field detection sensors 98 are positioned within respectivepole extension shoes 38. In the illustrated embodiment, magnetic fielddetection sensors 98 are positioned above respective pole extensionshoes 38. The tool 10 further comprising logic control circuit 23 whichis operative to receive an output signal from one or more of themagnetic field detection sensors 98 and determine from said outputsignal(s) at least one of the following operating states of the tool;whether the magnetic flux source 15 is switched on or off, whether thereis a ferromagnetic workpiece 17 in spatial proximity to one or more ofthe workpiece engagement surfaces 44 at the pole extension shoes 38,whether one or more of the workpiece engagement surfaces 44 at the poleextension shoes 38 about a workpiece 17, and whether abutment of aworkpiece 17 at one or more of the workpiece engagement surfaces 44 isadequate and within predetermined positioning thresholds.

In embodiments, the first magnetic field sensors 98 and the logiccontrol circuit 23 are housed/received within a further (second) housingcomponent 18 which itself may be of multi-piece construction and whichis coupled/secured to the first housing component 22, such as to providea compact-footprint end of arm magnetic coupling tool 10 with integratedmagnetic field detection and workpiece-tool interface detectioncapabilities.

In embodiments of the end of arm magnetic coupling tool 10, the magneticflux source 15, the first housing component 22 and the pole extensionshoes 38 are based around on-off switchable, dipole permanent magnetunits as developed by the Magswitch Group (of which the applicant ispart of). In particular, modified Magswitch ‘AR’ series switchablemagnetic flux sources may be used.

In embodiments, the first housing component 22 is a rectangular prismferromagnetic steel housing component with a central cylindrical bore24, in which two cylindrical, diametrically polarized rare-earthpermanent magnets 30, 32 are stacked (the latter providing the on-offswitchable magnetic flux source). One of the magnets 30 is fixed againstrotating within the cylindrical bore 24, while the other magnet 32 isfree to rotate upon external torque application using a suitableactuator 54 (pneumatic, hydraulic, or electric) interfaced with therotatable magnet 32. The steel housing 22 has a substantiallyrectangular foot print, wherein the central bore 24 is centered in thehousing 11 and dimensioned such that only thin well webs connect theopposing thick walled housing halves that provide integral poleextension pieces of the device, as described in U.S. Pat. No. 6,707,360,the entire disclosure of which is expressly incorporated by referenceherein. The lower magnet 30 is secured in the housing component 22 withthe N-S pole separation plane extending (bridging) between the thin wallwebs, so that the N- and S-poles of the magnet are extended into therespectively adjacent thick wall portion of the housing component 22(see FIG. 4 ).

When rotatable magnet 32 is rotated relative to fixed magnet 30 to alignthe N- and S-poles of the two magnets 30, 32, the steel housing 22becomes magnetically polarized, i.e, the housing itself provides part ofor both of the pole extension shoes to redirect the flux from themagnets 30, 32 towards the two, magnetically separated workpieceengagement surfaces 44 provided at one axial end of the housing at thelower surfaces of pole extension shoes 38. This, in turn, allows amagnetic circuit to form between the two opposing sides of the steelhousing 22. This turns the dipole flux source “on”, i.e. an on state.When rotatable magnet 32 is rotated relative to fixed magnet 30 topartially, but not completely align the N- and S-poles of the twomagnets, the steel housing 22 becomes magnetically polarized, i.e. thehousing 22 itself provides part of or both of the pole extension shoesto redirect the flux from magnets 30, 32 towards the two, magneticallyseparated workpiece engagement surfaces 44 provided at one axial end ofthe housing 22 at the lower surfaces of the pole extension shoes 38.This in turn allows a magnetic circuit to form between the two opposingsides of steel housing 22. The magnetic flux available at workpieceengagement surface 44 is reduced compared to the on state and approachesthe magnetic flux available at the workpiece engagement surfaces 44 ofthe on state the more aligned the N- and S-poles of the two magnets 30,32 become. This turns the dipole flux source 15 “partially on”, i.e. apartial on state. When top magnet 32 is rotated relative to fixed lowermagnet 30 to anti-align the N- and S-poles, the magnetic circuit isclosed within the housing 22, tuning the unit “off”, i.e. an off state,and effectively no usable magnetic flux can be “tapped” by a targetworkplace 17 when brought into contact with the workpiece engagementsurfaces 44, as would otherwise be the case in the on state or thepartial on state of the unit 10.

In embodiments, placement of magnetic field detection sensors 98relative to the pole extension shoes 38 provides a sensing system forthe switchable magnetic source 15. No matter what switching state (onstate, partial on state, off state) the switchable permanent magnet unit15 is in, there is always some magnetic field present outside thevicinity of the workpiece engagement surfaces 44 on the tower side ofthe pole extensions shoes 38, providing “leakage flux” pathways. Thisleakage may be very smell in the off state of the switchable permanentmagnet unit 15, and could be confined. Relevantly though, the amount ofleakage flux is heavily dependent on the internal magnetic circuit ofthe unit 10 itself, the on/partial on/off state of the unit 10, and themagnetic circuit formed between the unit 10 and the specific targetworkpiece 17.

When the unit 10 is in the off state wherein the two magnets 30, 32 areanti-aligned and forming a dosed magnetic circuit inside of the steelhousing 22, the unit 10 has very little leakage flux, though detectablewith sensitive magnetic field sensors 98 when properly placed. When theunit 10 is in the on state wherein the two magnets 30, 32 are alignedand in absence of a fully shunting target workpiece 17 at or inproximity of the workpiece engagement surfaces 44 there is a much higherlevel of leakage flux. When the unit 10 is in the partial on state thelevel of leakage flux is less than in the on state and more than in theoff state.

Further, in the on state of the partial on state, the amount of leakageflux is also determined by the quality of the working magnetic circuitformed between the pole shoes 38 of the unit 10 and workpiece 17 at thewar piece engagement surfaces 44 and the size, shape and material of theworkplace 17 itself. The quality of this magnetic circuit is determinedprimarily by the thickness and relative magnetic permeability of theworkpiece material, and the quality of contact between the magnetthrough the workpiece engagement surfaces 44 and the workpiece 17. Thehigher quality the magnetic circuit is the less leakage flux there is tobe detected on the side of the pole shoes 38 interacting with theworkpiece 17. The quality of the magnetic circuit is increased thethicker the workpiece 17 is, the higher the workpieces relative magneticpermeability, and the larger area of the contact between the pole shoes38 and the workpiece 17.

These ‘leakage’ effects allow for the magnetic field sensors 98 tomonitor and derive various operational states of unit 10 incorporatingMagswitch switchable permanent magnet units or other suitable switchablemagnet units. Magswitch “AR” series devices are normally designed foruse with detachable pole shoes 38. Pole shoe size and geometry can beselected to suit application fields and dual purpose pole shoes 38providing two differently contoured workpiece engagement surfaces atopposite axial ends may be employed. Additional pole shoe arrangementsare disclosed in US Provisional Patent Application No. 62/623,407, filedJan. 29, 2018, titled MAGNETIC LIFTING DEVICE HAVING POLE SHOES WITHSPACED APART PROJECTIONS, docket MTI-0015-01-US, the entire disclosureof which is expressly incorporated by reference herein.

In embodiments, a lower part of the first housing component 22 (which isquadrilateral in cross-section), where the lower fixed magnet 30 islocated, is recessed or machined on opposite external sides (i.e. at thethick walled portions) to provide respective shape-conformingreceptacles or recesses 29 for two ferromagnetic pole shoes 38. Inembodiments, the external shape of the two pole shoes 38 is chosen toprovide four continuous and step-free external faces of the housing 11when mounted thereto, i.e. these are rectangular prismatic or cuboid inshape.

The upper, um-recessed part of the first housing component 22 and thelower part of the first housing component with the exchangeably attachedcuboid pole shoes 38 form a continuous, as flux-leakage free as possibleflux delivery path towards the workplace engagement surfaces 44 providedat the free axial terminal ends of the pole shoes 38. In this case also,the flux detection surfaces 46 opposite the workpiece engagementsurfaces 44 will be provided at an upper terminal face of the firsthousing component 22, given the gap free mounting of the pole shoes 38at the receptacles. Pole shoes 38 may be lengthened to locate workpieceengagement surfaces 44 below a lower side 37 (see FIG. 3 ) of housingcomponent 22.

In embodiments, the EOAMT 10 will comprise, in addition to the firsthousing component 22, a second housing component 18 secured to on end ofthe first housing component opposite the workpiece engagement surfaces44 of the pole extension shoes 38. The second housing component 18 issubstantially non-ferromagnetic and includes at least two passage ways70 (see FIG. 5 ) extending preferably to terminal openings locatedopposite the flux detection surfaces 46 at the first housing component22 and receiving a respective one of two said first magnetic fielddetection sensors 98. This arrangement protects the sensors 98 fromexternal damage while equally ensuring that magnetic flux leakage fromthe flux detection surfaces 46 at the first housing component 22 issampled with minimal interference of other ferromagnetic components thatcould distort the magnetic field.

For sturdiness considerations, and noting the need for the secondhousing component 18 to have magnetic properties that do notsubstantially adversely affect shaping (e.g. bundling) of magnetic fieldlines passing through the flux detection surfaces 46 at the firsthousing component 22, aluminum alloys are a preferred material choice,and non-ferrous stainless steel could be used as well. Equally, suitableimpact resistant polymer materials (reinforced if desired) having thenecessary low relative magnetic permeability values, can also find use.In this context, tow relative magnetic permeability is one which is 4 to6 orders of magnitude tower than that of the material used in themanufacture of the pole shoes 38 and the first housing component 22. Inembodiments, the first housing component 22 and the pole shoes 38 aremade from the same material.

The preferably also rectangular prismatic second housing component 18can advantageously serve to house an actuator 54 which interfaces withthe rotatable magnet 32 received in the first housing component 22 toswitch the magnetic flux source 15 between an on state, an off state,and one or more partial on states, and to seal the bore 24 in which themagnets 30, 32 are received against infiltration of dust and water, inaddition to housing the first sensors 98 in a protected manner againstenvironmental influences.

In embodiments, the logic control circuit 23 is operative to receiveoutput signals from the one or more of the first magnetic field (and anyadditional) detection sensors 98 and determine from said outputsignal(s) one or more of the operating states of the tool 10. Inembodiments, the logic control circuit 23 comprises a central controlboard, preferably using a printed circuit board which containspre-programmed or programmable microprocessor, with analog to digitalconverters (ADCs) for sensor signal sampling and conditioning ifrequired, and additional transistors that allow a GPIO (general-purposeinput/output) of the processor to be interfaced to industrial 24V logic.The board will advantageously also host power conditioning, to take 24 Vfrom an industrial power supply and regulate it to 5 or 3.3 V asnormally used by industrial robotics microprocessors and circuitcomponents as well as provide the working voltage for the magnetic fieldsensors.

In addition, the central control board may be provided with a series ofblank headers, intended to accept a communications module that allowsthe control board to interface with external control electronics, suchas robot controller 770 (see FIG. 25 ). This interface may be as simpleas a discrete I/O connection, sending single bit On-Off signals over 24V logic lines, or as advanced as a full industrial Ethernet connection.

As noted, the central control board will advantageously use ADCs forsensor signal sampling, but could equally incorporate direct analoginputs, with filtering and the required signal conditioning, that allowthe microprocessor to receive and process signals from the firstmagnetic field sensors, but equally other sensors, e.g. temperaturesensors 31, that may be incorporated into the first and/or secondhousing component.

The first magnetic field sensors 98 could be simple scalar magnetometersused to measure the total strength of a magnetic field. In embodiments,the magnetic field sensors 98 are preferably more complex anddifferentiating vector magnetometers, such as solid-state linear HallEffect sensors, in particular of bi-directional type, magneto resistivesensors that can be incorporated in integrated circuits, etc. LinearHail Effect sensors can have a very small form factor and embodied insolid state ICs (e.g. Honeywell SS39ET/SS49E/SS59ET series) and aretherefore a preferred embodiment of the first magnetic field sensors.Because of the small form factor (e.g. 3×3×1.5 mm), it is possible toincorporate various Linear Halt Effect sensors having different magneticfield detection ranges and sensitivities, for example, in providing thefirst magnetic field sensors 98, and which using suitable logiccircuitry can be switched so that the respective sensor output signalscan be processed and if necessary combined to obtain a clearer pictureof the magnetic field near the flux detection surfaces 46 of the poleextension shoes 38 of the EOAMT 10, if required. In embodiments, themagnetic field sensors 98 are three dimensional sensors having thecapability to sense magnetic fields in three orthogonal directions. Anexemplary magnetic field sensors is Model No. TLV493D-A1B6 threedimensional magnetic sensor available from Infineon Technologies AGlocated at Am Campeon 1-15, 85579 Neubiberg in Germany.

As noted, in embodiments additional sensors, such as temperature sensors31 may be integrated in suitable cavities at the first housing component22. An evaluation circuit (more precisely the software program used inthe microprocessor to perform: signal evaluation and analysis) of thelogic control circuit 23 will then compensate for temperature dependentdrift of the magnetic field sensors 98 to yield more accurate EOAMT 10positioning data.

Further, in embodiments, additional magnetic field sensors 98 areincluded. Referring to FIG. 14 , a representative top view of unit 10,magnetic field sensors 98 are positioned as described herein with afirst magnetic field sensor 98 being positioned in a left side half 101of the magnetic coupling tool 10 and a second magnetic field sensor 98being positioned in a right side half 103 of the magnetic coupling tool10. Additionally, a third magnetic field sensor 98 is positioned in afront half 105 of the magnetic coupling tool 10 and a fourth magneticfield sensor 98 is positioned in a rear half 107 of the magneticcoupling tool 10. The front half 105 including a first portion 109 ofthe left side half 101 and a first portion 111 of the right side half103. The rear half 107 including a second portion 115 of the left sidehalf 101 and a second portion 115 of the right side half 103. Theaddition of the third and fourth magnetic field sensors 98 providesadditional sensor values which may be used to determine variousoperating states of the magnetic coupling tool 10. For example, logiccontrol circuit 23 based on the outputs of the four magnetic fieldsensors may determine an orientation of the workpiece engagementsurfaces 44 relative to the ferromagnetic workpiece 17 in two rotationalaxes, such as left-to-right tilt and front-to-back tilt.

Turning then to functional blocks of the logic control circuit 23. Thesimplest piece of information required about the EOAMT 10 is that of theswitching state of the magnetic flux source 15 (unit), i.e. is the unitin the off state, the on state, or a partial on state. In the off state,the EOAMT 10 has extremely little or even no leakage flux. In the onstate, even on a near perfect magnetic working circuit with a workpiece17, the EOAMT's switchable permanent magnetic unit 15 has considerablymore leakage flux than in the off state. Therefore, in a calibrationprocess, the reading of one or more of the first magnetic field sensors98 in the off state of the EOAMT 10 can be stored in a memory 33 (seeFIG. 13 ) associated with the microprocessor of the logic controlcircuit 23 as a calibrated or hard coded value, and when themagnetometer reading rises above this off-state-value or some offsetabove this off-state value, the EOAMT 10 can be considered in the onstate or a partial on state. When the magnetometer reading is at orclose to the calibration stored value, the EOAMT 10 can be considered inthe off state. In embodiments, through a calibration process, thereading of one or more of the first magnetic field sensors 98 in adesired partial on state may be stored in memory 33 as a calibrated orhard coded value, and when the magnetometer reading rises to a specificstored reading or within some percentage of the specific stored reading,the EOAMT 10 can be considered to be in the corresponding partial onstate.

Another functional block of the logic control circuit 23 may be used todetermine if there is a ferromagnetic workpiece underneath one or boththe workpiece engagement surfaces 44 of the two magnetic pole extensionshoes 38 of the EOAMT 10, when the flux source unit is turned on orpartially on. When no target part is present for the EOAMT tomagnetically attach to (see FIG. 15 ), there is no ‘true’ (i.e. externalworking) magnetic circuit between the two pole shoes 38. Assuming thatany workpiece 17 is sufficiently spaced apart from the pole shoes 38 soas to not distort the magnetic field, the flux would extend through airbetween the lower terminal ends of the pole shoes 38 (primarily betweenthe workpiece engagement surfaces 44), effectively representing leakageflux. This also causes a high leakage flux to be present at the fluxdetection surfaces 46 of the pole extension shoes 38, and consequently arelatively high reading at the magnetic field sensors 98. By storingthis “max leakage flux” for a given on state or partial on state inmemory 33 associated with the microprocessor of the logic controlcircuit 23, either hard coded (given that this value would beinvariable), or from a calibration run, in normal operation of the EOAMT10 it is possible to determine if there is a workpiece present or not,by placing the magnetic switching unit in the on state or partial onstate corresponding to the stored “max leakage flux” reference value andcomparing a current sensor output with the stored “max leakage flux”reference value for the on state or the partial on state.

In addition to detecting a presence or absence of workpiece 17, logiccontrol circuit 23 may also provide an indication of a spacing of theworkpiece engagement surfaces 44 from the workpiece 17 when the presenceof a workpiece detected (the current sensor value is below the stored“max leakage flux” for presence detection). In embodiments, logiccontrol circuit 23, is configured to determine if at least one of theplurality of workplace engagement surfaces 44 is proximate to theferromagnetic workpiece 17. In one example, logic control circuit 23determines if one of the workpiece engagement surfaces 44 is proximateto workpiece 17 when the current value for the corresponding sensor 98falls below a threshold value. The threshold value may be determined andstored in memory 33 during a calibration run and may correspond to aknown spacing between the workpiece engagement surface 44 and theworkpiece 17 (see FIG. 16 ). In one embodiment, a plurality of thresholdvalues are stored on memory 33, each corresponding to a respective knownspacing. The plurality of stored threshold values permits logic controlcircuit to provide better approximation of the spacing between theworkpiece engagement surface 44 and the workpiece 17 and to distinguishbetween a first spacing (see FIG. 16 ) and a second, smaller spacing(see FIG. 17 ). An advantage, among others is that the ability toaccurately determine proximity of a workpiece allows a robotic system(see FIG. 25 ) to move at a higher speed until magnetic coupling unit 10is within a first spacing from workpiece 17 and thereafter move at aslower speed until contact is made with workpiece 17. In embodiments,for the various calibrations runs and values discussed herein, separatecalibrations runs or values are performed for different types offerromagnetic materials due to fact that target sensor readings maydiffer based on the respective size, shape, material, etc. of the targetferromagnetic workpiece.

In embodiments, logic control circuit 23 is configured to determine anorientation of the first workpiece engagement surface 44 and the secondworkpiece engagement surface 44 relative to the ferromagnetic workpiece17. In one example, the orientation of the first workpiece engagementsurface 44 and the second workpiece engagement surface 44 relative tothe ferromagnetic workpiece 17 is determined by a comparison of anoutput of the first magnetic field sensor 98 and an output of the secondmagnetic field sensor 98. A first spacing between the first workpieceengagement surface 44 and the ferromagnetic workpiece 17 and a secondspacing between the second workpiece engagement surface 44 and theferromagnetic workpiece 17 are determined by logic control circuit 23 tobe generally equal when the output of the first magnetic field sensor 98and the output of the second magnetic field sensor 98 satisfy a firstcriteria. In one example, the first criteria is that the output of thefirst magnetic field sensor 98 is within a threshold amount of theoutput of the second magnetic field sensor 98. An example thresholdamount is an absolute difference. In another example, the thresholdamount is a percentage difference. When the first criteria is satisfied,the workpiece engagement surfaces 44 have generally equal spacingrelative to the workpiece 17 (see FIG. 17 ). When the first criteria isnot satisfied, the workplace engagement surfaces 44 are angled relativeto the workpiece 17 (see FIG. 18 ). If a third and fourth magnetic fieldsensor are incorporated, such as shown in FIG. 14 , an angle about apitch axis (see FIG. 19 ) may also be determined in addition to theangle about the roll axis depicted in FIG. 18 .

In addition to these tool status and workpiece detection capabilities,the presence and specific location of at least two magnetic fieldsensors 98 in the specified location near the pole shoes 38, providesmore advanced feedback. This is because situation-dependent, potentiallyuneven distribution of leakage flux around the individual pole extensionshoes can be sampled, compared and evaluated.

In embodiments, in the on state (equally applicable to a known partialon state) of the magnetic flux source 15, if the workpiece engagementsurfaces 44 of the pole extension shoe 38 with the magnets' North Poleshas good contact with a workpiece 17, but the pole extension shoe 38with the magnets' South Poles has poor contact with the workpiece 17(see FIG. 20 ), there wilt be more leakage flux on the South Pole thanthe North Pole. The first magnetic field sensor 98 above the North Poleand the first magnetic field sensor above the South Pole 98 are able todetect this condition, and the sensor 98 above the South Pole willreturn a higher reading than the sensor 98 above the North Pole. In oneexample, bidirectional Hall Effect sensors are used for sensors 98.Therefore, by reading each sensor 98 separately and comparing thereadings between them, logic control circuit 23 is able to determinethat the South Pole has poor contact on the workpiece 17. Inembodiments, the logic control circuit has a functional block to performsuch evaluation, implementable in hardware and microprocessor software.In one example, logic control circuit 23 determines the South Pole haspoor contact when a difference in the readings of the North Pole sensor98 and the South Pole sensor 98 exceed a stored threshold amount.

In embodiments, logic control circuit 23 is configured to determine if aplacement of the first workpiece engagement surface 44 and the secondworkpiece engagement surface 44 relative to the ferromagnetic workpiece17 are within a target zone 121 on the ferromagnetic workpiece 17 (seeFIG. 21 ). In one example, the placement of the first workpieceengagement surface 44 and the second workpiece engagement surface 44relative to the ferromagnetic workpiece 17 are determined by logiccontrol circuit 23 to be within the target zone 121 (FIGS. 21-23 ) ofthe ferromagnetic workpiece 17 when both an output of the first magneticfield sensor 98 satisfies a first criteria and an output of the secondmagnetic field sensor 98 satisfies a second criteria. An exemplary firstcriteria is that the output of the first magnetic field sensor 98 iswithin a first range of magnetic flux values and an exemplary secondcriteria is the output of the second magnetic field sensor 98 is withina second range of magnetic flux values.

Referring to FIGS. 21-23 , target zone 121 is illustrated. Workpiece 17is illustrated as a sheet of material having a right end 125 and a leftend 129. Target zone 121 is the portion of workpiece 17 between a firstoffset 123 from the right end 125 of workpiece 17 and a second offset127 from the left end 129 of workpiece 17. In one example, as tool 10approaches and/or exceeds second offset 127, the leakage flux associatedwith the left pole tension shoe 38 is higher than the leakage fluxassociated with the right pole extension shoe 38 due to the left poleextension shoe approaching left end 129 of workpiece 17. In similarfashion, as tool 10 approaches and/or exceeds first offset 123, theleakage flux associated with the right pole extension shoe 38 is higherthan the leakage flux associated with the left pole extension shoe 38due to the right pole extension shoe approaching right end 125 ofworkpiece 17. Although shown as a linear target zone 121, atwo-dimensional target zone 121 may be defined for a length and a widthof workpiece 17. In one example a calibration run is executed whereintool 10 is placed at each of first limit 123 (see FIG. 23 ) and secondlimit 127 (see FIG. 22 ) and the corresponding leakage flux values forthe magnetic flux sensors 98 at both limits are stored in memory 33. Thetwo leakage flux values stored for the first limit position (see FIG. 23) are stored in memory 33 as “Limiting Position 1” (two values, one foreach sensor 98). The two leakage flux values stored for the second limitposition (see FIG. 22 ) are stored in memory 33 as “limiting Position 2”(two values, one for each sensor 98). In embodiments, the first range ofthe first criteria are the values between and including LimitingPosition 1 and Limiting Position 2 for one of the magnetic field sensors98 and the second range of the second criteria are the values betweenand including Limiting Position 1 and Limiting Position 2 for the otherof the magnetic field sensors 98. Assuming the first range of valuescorrespond to the left side sensor 98 of unit 10 and the second range ofvalues correspond to the right side sensor 98 of unit 10, logic controlcircuit 23 determines that a left end of the tool 10 is positionedoutside of the target zone 121 when the second criteria is satisfied andthe first criteria is not satisfied and likewise that a right end of thetool 10 is positioned outside of the target zone 121 when the firstcriteria is satisfied and the second criteria is not satisfied.

In embodiments, using (storing) ‘Limiting Position 1’ and LimitingPosition 2’ calibrated values on memory 33 allows a tool user tocalibrate the workpiece present signal to only come on when a specificmagnetic work circuit is termed (if calibrated as the same position) orwithin a range of magnetic working circuits (if calibrated as 2different positions). The North and South pole signal positions caneither be the equivalent of the “max leakage” position of LimitingPosition 1/2 or it can be outside of that in a greater leakage position.These calibrations are what allow for so called double blank detection(DBD) and part specific or range specific confirmation. The freedom forthe North and South pole positions to be outside :of the limitingpositions is intended to give the user more freedom, especially if theyare landing near edges on thinner steel sheets.

In embodiments, it is also possible to use this multisensory approach toprovide additional tool status data. In the above situation, beyond justcomparing the two sensor readings to determine a general state of thetool and the presence or absence of a workpiece in proximity of theworkpiece engagement surfaces of the pole extension shoes, by takingmere differentiated and precise magnetic field measurements from eachsensor when in closer proximity to the workpiece (i.e. presence alreadydetected, but proximity not yet quantified) and performing calculationson the value of each sensor's signal and the value of the differencebetween the magnetometer readings, one can determine the orientation ofthe tool relative to the workpiece, such at what angle a magnet gripperincluding the tool 10 is sitting relative to a flat steel workpiece.

Taking this even further using calibration runs of tool 10 with respectto a predefined workpiece having known parameters (size, shape,material, etc.) and by storing into memory of the evaluation circuitdata obtained from processing of sensor output signals during thevarious calibration runs, it is possible to completely determine theorientation end distance to a workpiece target surface relative to theEOAMT position, even before the pole extension shoes contact theworkpiece, in particular if additional magnetic field sensors are placedin locations other than the ones previously specified such as shown inFIG. 14 . As the unit 10 emits leakage flux in any state, even the offstate, very sensitive sensors can respond to small variations in theleakage flux emanating from the pole shoes at the sensor detectionsurfaces in the off state. When an EOAMT in the off state or a knownpartial on state approaches a workplace, then, adequately sensitivemagnetometers can indicate proximity to component, and can deliversignals which are converted into control signals for the robotic arm inacting as a sort of “vision” for an otherwise blind robot.

For example, assuming that a total of four magnetometers are present,one at the flux detection surface of the North pole shoe and one at theflux detection surface of the South pole shoe associated with themagnetic flux source, as previously noted, and two additional sensors atother locations, such as shown in FIG. 14 , when moving the EOAMTtowards the workpiece with one of the sensors moving closer (in absoluteterms) than the others, leakage flux lines near that sensor wouldincrease in density, focusing themselves toward the workpiece. Inbringing the EOAMT even closer to the workpiece (without changingspatial attitude and translational direction of the housing componentcoupled to the end of the arm of the robot, the flux lines wouldredistribute more intensely across the housing component, with thedensity of flux lines on the nearest sensor being inversely proportionalto the distance between the sensor and the workpiece. This produces aneven higher reading in the magnetometer over the dose-proximity sensor.By comparing the close proximity magnetometer output to the signaloutput from the other 3 magnetometers, and by evaluating the data onecan tell where and how close the workpiece is to the working faces ofthe EOAMT, given the known spatial relationships between the sensors andthe working face of the pole extension shoes.

In performing accurate calculations on the outputs of the magnetometersof the EOAMT, other functionalities can be enabled when the magneticflux source is switched on and contact is established with theworkpiece. There is a direct relationship between the amount of magneticflux in a working magnetic circuit, and the amount of physical forcethat the working magnetic circuit can withstand, which in the case of amagnetic coupling tool corresponds to the tools payload. As the leakageflux from a permanent magnet depends on how much of the magnetic flux is‘consumed’ (i.e. bound) in the primary working circuit, there is acorrelation between the leakage flux and the maximum payload that can besustained by the coupling tool. The microprocessor of the logic controlcircuit 23 is programmed, in one embodiment with the appropriateformulae and calibration runs can be performed such that the combinedreadings of the magnetometers on the tool can be used to derive a moreexact holding force of the EOAMT than with known devices: This could beused as a “safety check,” to make sure that the EOAMT is able to theworkpiece before being moved by the robot.

In all of these situations, the microprocessor of the logic controlcircuit 23 is responsible for accepting input from each of themagnetometers 98 of the EOAMT and performing calculations andcomparisons. The microprocessor then determines various tool statesbased upon the calculations. In embodiments, tool 10 communicates thedetermined tool states and feedback points to an external robotcontroller 770 (see FIG. 25 ). This is handled by either the 24V I/O ora communications module 39. Once the feedback has been communicated tothe robot controller 770, the robot controller 770 is then able toadjust an orientation of tool 10 and operation to address challenges orissues in operation.

It will be appreciated that the logic control circuit 23 comprises therequired components to perform isolation, filtering and amplification ofsignals provided by the sensors for processing by the on-boardmicroprocessor of the EOAMT 10.

In embodiments., the EOAMT 10 incorporates input devices 41 and outputdevices 43. Exemplary input devices include buttons, switches, levers,dials, touch displays, soft keys, and communication module 39. Exemplaryoutput devices include visual indicators, audio indicators,. andcommunication module 39. Exemplary visual indicators include displays,lights, and other visual systems. Exemplary audio indicators includespeakers and other suitable audio systems. In embodiments, tool 10includes simple visual status indicators, in the form of one or moreLEDs positioned behind LED window 106, which are driven by themicroprocessor of logic control circuit 23, to indicate when apredefined Tool status is present or absent (e.g. Red LED on whenmagnetic flux source 15 is off, Green LED blinking fast when magneticflux source 15 is on and proximity of target 17 is detected, Green LEDslower blinking with Yellow LED on when contacting target 17 outsideintended specific area 121 on to et 17 (e.g. partially complete magneticworking circuit) and Yellow LED off with steady Green LED on, showingtool engagement within threshold limits, showing safe magnetic couplingstate.

Referring to the FIG. 1-29 , additional details regarding embodiments oftool 10 are provided. Referring to FIGS. 1 and 2 , an embodiment of tool10 is illustrated that can be integrated as an end of aim tool in arobotic material handling apparatus 700 (see FIG. 25 ) by way offastening structures 12, 14 which in this case are threaded bores and adowel bore in a housing component of tool 10 adapted to receivefastening bolts (not shown). Other arrangements/interfaces for securingtool 10 to a robotic arm 704 of robotic system 700 or other type ofpositioning apparatus are known to the skilled person.

Tool 10 incorporates magnetic field detection sensors 98, as well as, anon-board sensor output signal processing circuit with integratedmicroprocessor, logic control circuit 23, which in turn provides avariety of tool status information data that can be displayed visuallyand/or used by a controller 770 of robotic system 700 to determinewhether the tool 10 is in an on state, a partial on state, or off state;whether the tool 10 has been positioned correctly (within predefinedthresholds) on a target zone 121 of a workpiece 17 (see FIG. 21 );whether a safe magnetic working circuit has been established betweentool 10 and target workpiece and also to assist in positioning tool 10by the robotic arm 704.

Tool 10 includes two subassemblies, a switchable permanent magnetassembly 16 and an actuator and electronic sensor and feedback assembly18. FIG. 3 is an exploded view of the entire tool 10, whereas FIGS. 4and 5 respectively show the permanent magnet assembly 16 and theactuator 54 and electronic sensor and feedback assembly 18.

Referring to FIG. 4 , an embodiment of a switchable permanent magnetdevice 20 as described in U.S. Pat. No. 7,012,495 (Magswitch), theentire disclosure of which is expressly incorporated by referenceherein, is illustrated. Switchable permanent magnet device 20 is amodified version of an AR type Magswitch unit as manufactured and soldby Magswitch Technology Inc. Device 20 includes a ferromagnetic steelhousing 22, illustratively of rectangular foot print, essentially aunitary rectangular prismatic body with an upper portion whose width islarger than a lower portion with both portions having the same depth. Inone embodiment, housing 22 is a multi-piece housing. A circular bore 24extends axially from the bottom to the top of housing 22, with its axiscoinciding with the intersection of the width and depth symmetry planesof housing 22, so that a small web 26 of material is left standing onopposite depth ends of housing 22, which subdivide housing 22 inessentially magnetically isolated portions along the height of housing22. The wall thickness of the width-ward housing portions 28 issubstantial and sufficient to fully carry magnetic flux provided by twocylindrical, diametrically magnetized rare earth permanent magnets 30,32 which are received in bore 24. A shunt plate 34 is inserted to dosethe bottom end of bore 24. Bottom magnet 30 is fixed against rotation inbore 24 in such an orientation that the N-S pole separation plane (p) ofmagnet 30 bisects the web portions 26 and polarizes the oppositewidth-ward housing portions with the respective N- and S-polarities ofthe dipole magnet 30. Top magnet 32, despite having a hexagonal prismdepression on its upper face to allow for hexagonal prism drive shaft 36to be inserted into it, has ideally and as far as possible the samemagnetization characteristics as lower magnet 30.

Two ferromagnetic pole shoes 38, illustratively of essentiallyrectangular prismatic configuration (but for chamfered edges at anoutside face), of a material magnetically compatible with or the same ashousing 22, are mounted to the width-ward sides at the lower portion ofhousing 22 to complement the shape of the upper portion of housing 22,using bolts 40 and locator pins 42. Pole shoes 38 preferably extendbeyond a lower side 37 (see FIG. 3 ) of housing 22, but areillustratively shown as generally flush with the lower side 37 ofhousing 22. Pole shoes 38 define at a lower face respective workpieceengagement surfaces 44 which in the illustrated embodiment are planar,but could be of different geometry and/or contoured to form fittinglyabut against a target surface of a workpiece 17 to be magneticallycoupled to and handled by tool 10. The fit of pole shoes 38 to thereceptacles defined at the lower portion of housing 22 is such as tominimize or indeed essentially avoid magnetic circuit air gaps; in otherwords, the thick-walled width-ward portions of housing 22 and the poleshoes 30 together form a magnetic flux path from the magnets 30, 32 tothe top and bottom axial end faces of housing 22.

As noted, the pole shoes 38 define at their lower terminal end thetool's workplace engagement (or working) surface(s), whereas the topfaces of the thick-walled width-ward portions of housing 22 define whatwill herein be termed flux detection surfaces 46. In absence of anexternal magnetic working circuit, and even when such is created,magnetic flux lines pass through both the workpiece engagement surfaces44 at pole shoes 38 and flux detection surfaces 46 of housing 22.

For further details on such switchable permanent magnet units 20,compare Magswitch Technology technical information of its products whichis publically available, including magnetic rating of Magswitch ARdevices. For example, an AR 50 coupling unit has a max. workpiece breakaway rating of 249 kg with a safe working load of 62 Kg and safe sheerload of 31 Kg, the magnets having a flux output to cause full saturationof a ferromagnetic workpiece having a thickness of 9.5 mm and bottomface footprint area of 52×64 mm.

Turning then to FIG. 5 , the actuator and electronic sensor and feedbackassembly 18 (as identified in FIG. 2 ) it illustrated. Referring toFIGS. 3 and 5 , assembly 18 comprises a four part housing assembly 48whose parts serve different functional purposes.

A lower rectangular-footprint act for housing part 50 is made (machinedand/or cast) from aluminum and includes a rectangular depression 52 witha through passage opening towards the lower face of housing pad 50,which serves to house a rotary actuator 54.

Rotary actuator 54 has a torque output shaft 56 which in the assembledstate of tool 10, in which lower housing part 50 is hermetically securedto the top of the magnet assembly's housing 22 using four fasteningbolts 58 which extend through four bores 59 in lower housing part 50 andengage with threaded bores 60 on the top face of housing 22. Torqueoutput shaft 56 is inserted into hexagonal drive insert 36 present atthe upper magnet 32. This enables actuator 54 to impart selective torqueto rotate top magnet 32 in its housing 22 to turn the switchablepermanent magnet device 20 between the off state, the on state, and apartial on state. Referring in this context to and as may be gleanedfrom FIG. 4 , the lines across the upper faces of both magnets 30, 32represent the respective separation planes of the North and South activepoles of magnets 30, 32.

When the north and south poles of both magnets 30, 32 are on the samewidth-ward side of housing 22 such that the north pole of permanentmagnet 32 completely overlaps the north pole of permanent magnet 30,device 20 is in the on state, providing flux past workpiece engagementsurfaces 44 at pole shoes 38 and flux detection surfaces 46 at housing22. When the north and south poles of both magnets are on the samewidth-ward side of housing 22 such that the north pole of permanentmagnet 32 only partially overlaps the north pole of permanent magnet 30,device 20 is in the partial on state, providing flux past workpieceengagement surfaces 44 at pole shoes 38 and flux detection surfaces 46at housing 22. When the north and south pole of both magnets 30, 32 areon the opposite sides (i.e. anti-aligned) such that the north pole ofpermanent magnet 32 completely overlaps the south pole of permanentmagnet 30, the device is in the off state and flux is confined withinthe housing 22 and magnets 30, 32. Additional details on exemplaryactuation and sensing systems are provided in U.S. Pat. No. 7,012,495and US Provisional Application No. 62/634,783, filed Feb. 23, 2018,titled VARIABLE FIELD MAGNETIC COUPLERS AND METHODS FOR ENGAGING AFERROMAGNETIC WORKPIECE, docket MTI-0016-01-US, the entire disclosuresof which are expressly incorporated by reference herein.

Lower housing part 50 also includes two coupling conduits 62 throughwhich the actuator 64 receives hydraulic or pneumatic fluid, dependingon the actuators make-up, to rotate its output shaft selectively to turnunit 20 on and off. In one embodiment, actuator 54 is an electricactuator and receives power from robotic system 700. Exemplary electricactuators include stepper motors. Reference number 64 in FIGS. 3 and 5references a flag and hard stop that are provided to limit rotation andprovide reference stops/positions for the upper magnet 32 of unit 20 inthe on state and the off state rotational orientations. Retractable pinsmay be included to selectively provide reference stops for upper magnet32 in various partial on states as described in US ProvisionalApplication No. 62/634,783, filed Feb. 23, 2018, titled VARIABLE FIELDMAGNETIC COUPLERS AND METHODS FOR ENGAGING A FERROMAGNETIC WORKPIECE,docket MTI-0016-01-US, the entire disclosure of which is expresslyincorporated by reference herein.

In embodiments, logic control circuit 23 monitors the rotationalposition of magnet 32 to verify that magnet 32 has been moved to theappropriate reference position for known partial on states and the onstate. In examples where actuator 54 is a stepper motor, logic controlcircuit 23 monitors a position signal from the stepper motor andcompares that to a stored position value to determine if magnet 32 in inthe requested partial on or on state.

In embodiments, magnetic coupling device 10 includes a brake, such as africtional brake which may interact with a rotatable member coupled topermanent magnet 32. The frictional brake may be actuated to maintainthe current position of rotatable member and hence the current positionof permanent magnet 32.

In embodiments, actuator 54 is a stepper motor and the ability of thestepper motor to hold its output shaft at a current position also holdspermanent magnet 32 at a current position and hence magnetic couplingdevice 10 in a current state (on state, off state partial on state).

An intermediate aluminum (or other non-ferromagnetic metallic) housingpart 66 of housing assembly 48 has a rectangular footprint and issecured to the lower housing part 50 by the above mentioned fasteningbolts 58. Intermediate housing part 66 has a rectangular recess 68 withbores 69 on the width-ward ends of recess 68 extending from top tobottom, with the width-ward end bores 69 locating outside therectangular depression 52 in lower housing part 50 and coinciding withrespective cylindrical passage channels 70 that extend either from thetop to the bottom face of lower housing part 50 or from the top to end asmall distance from the bottom face.

On top of intermediate housing part 66 is a rectangular frame-like upperhousing part 72, also made from non-ferromagnetic metal material, whoseupper open end is closed by a rectangular non-ferromagnetic cover plate74 which by way of four fastening screws 78 extending through bores 78at the four corners of upper housing part 72 is sandwiched in sealingmanner between cover plate 74 and intermediate housing part 66. It willbe noted that two of the fastening screws 76 secure in threaded bores 80on one width-ward side on the top of intermediate housing part 66,whereas the other two fastening screws 76 are seated and secured at twothreaded bores 82 on a width-ward opposite side in a top block portion84 of lower housing part 50, so that all housing parts 50, 66, 72 and 74of housing assembly 48 of actuator and electronic sensor and feedbackassembly 18 secure safely to one another.

Referring to FIG. 5 , actuator and electronic sensor and feedbackassembly 18 further includes a magnetic field sensor and sensor signalprocessing circuit unit 90 which is part of logic control circuit 23 andthat will now be described with reference to FIGS. 6 and 7 . Unit 90comprises two PCBs (printed circuit boards), a main control PCB 92 and amagnetometer sensor PCB 94 comprising two leg portions 96 which at theirrespective terminal ends each support/mount a magnetic flux sensor 98 ofLinear Halt Effect type as mentioned above.

Main control PCB 92 includes a microcontroller (not illustratedseparately), an M12 electronic connector 100 for interfacing I/O signalsto/from the sensors and microcontroller with external equipment, and aboard-to-board connector 102 on its underside for coupling with acomplimentary board-to-board connector 104 located in the horizontal legof PCB 94; connector 102 and 104 serve, beyond providing a mechanicalconnection between the PCBs, to conduct signals between electroniccomponents on the respective boards, as is known in industry.

Referring to FIG. 3 , main control PCB 92 will locate and be secured inthe assembled state of upper housing assembly 48 within frame-like upperhousing part 72, the board-to-board connectors 102 and 104 will come tolocate within the rectangular through-passage 68 of intermediate housingpart 66, and the leg portions 96 of magnetometer sensor board PCB 94will extend past rectangular through-passage 68 of intermediate housingpart 66 into the two cylindrical passage channels 70 in lower housingpart 50. The overall arrangement ensures that the Hall Effect sensors 98of PCB 94 will come to be securely located in a defined position a smalldistance away from the flux detection surfaces 46 of housing 22. Inessence, this arrangement ensures that one magnetic flux sensor 98 ofmagnetometer sensor board PCB 94 is positioned over the North Pole ofthe switchable permanent magnet device 20 (one of the pole extensionshoes 38), and the other sensor 98 is positioned over the South Pole(one of the pole extension shoes 38).

The magnetic field sensor and sensor signal processing circuit unit 90has a layout and electronic components that allow magnetic flux signalsto be sent electrically from sensors 98 to the microcontroller/processoron the main PCB 92 where these signals can be conditioned andinformation embedded in the signal can then be processed by themicrocontroller through a series of algorithms to provide tool statefeedback via an M12 electronic connector 100 which is secured to coverplate 74 using M12 pressed screw connector 105 used for attaching an M12cable assembly to the M12 electrical connector 100 linked to themicrocontroller.

Main PCB 92 may incorporate one or more output devices 144,illustratively LEDs, that receive status signals from themicrocontroller/processor to provide a visual representation of certaintool states, beyond using the signals for an external control device.These tool states can be appreciated visually by an operator through anLED window 106 present in a wall of the frame-like upper housing part72. The tool states will in any event include: magnet unit 20 ofswitchable permanent magnet assembly 16 on or off, North Pole pole shoe38 (i.e. its workpiece engagement surface 44) on target or not (withinsettable thresholds, as explained below), which is indicative of thenorth pole shoe having a good magnetic hold on the workpiece), SouthPole pole shoe 38 (i.e. its workpiece engagement surface 44) on targetor not (within settable thresholds, as explained below), which isindicative of the south pole shoe having a good hold on the workpiece),and workpiece presence with overall good pull force exertion (both polehave good contact on the workpiece).

In an exemplary embodiment, the following operations were handled bytool 10: (1) Microprocessor (having an ADC unit) used to read magneticsensor values; (2) Microprocessor used to read multiple sensors values;(3) Sensor readings used to light up tool status indication LEDs atcertain sensor values; (4) Sensor readings used to light up an LED forthe tool being On/Off; (5) an averaging function was created on themicroprocessor to averages the sensor values; (6) A calibration functionwas created incorporating the averaging function to determine the onvalues for the sensors; and (7) The calibrated values from thecalibration function were used to determine if the poles were offtarget, outside the target zone 121. In this exemplary embodiment of theEOAMT 10, a STM320F038 Discovery board was initially used followed by acustom designed main PCB board using STM32F030R8T6, and software codedand uploaded into memory of the processor, to perform the tool'sfunctional settings, including calibration of the tool's sensors andcontroller.

An exemplary calibration procedure for the tool 10 includes placing thetool with its two workpiece engagement surfaces 44 against a workpiece17 to be handled by the tool 10, in varying positions, multiple samplingof magnetic field sensor data at the sensors 98 located in closeproximity to the flux detection surfaces 46 of the magnet unit's housingfor each of the varying positions, averaging of sampled data, andstoring threshold values in memory 33 against which live sensor datasampled during operation of the tool can be compared to determine toolstatus. To this end, the STM320F038 Discovery board was configured toallow toggling of data input. A three step calibration procedure thenincludes, in the specified order;

-   -   1. Toggle the calibration input of input devices 41 (see FIG. 13        ).        -   a. Now the tool is in calibration mode.        -   b. Wait for the power LED to stop flashing.    -   2. Place the tool with its workpiece engagement surfaces against        a workpiece with ‘ideal’ contact and turn or the magnetic flux        unit to an on state or alternatively to a known partial on        state.    -   3. Toggle the calibration input.        -   a. Wait for the power LED to stop flashing.        -   b. Once the power LED stops flashing, turn the magnetic flux            unit of the tool.    -   4. Orient the tool with its workpiece engagement surfaces on the        workpiece so that the S-Pole pole shoes is at the extent of what        a tool operator (user) wants to be the on target value and turn        the unit on to an on state or alternatively to a known partial        on state.    -   5. Toggle the calibration input.        -   a. Wait for the power LED to stop flashing.        -   b. Once the power LED stops flashing, turn off the tool's            magnetic flux source.    -   6. Orient the tool on the part so that the N-Pole pole shoe is        at the extent of what the user wants to be the on target value        and turn the unit on to an on state or alternatively to a known        partial on state.    -   7. Toggle the calibration input.        -   a. Wait for the power LED to stop flashing.        -   b. Once the power LED stops flashing, turn off the unit.    -   8. Once the power LED stops flashing, the tool will go back into        sensing mode. At this point in time, the state outputs of the        tool should be functioning properly for the on state or known        partial on state that was calibrated. If this is not the case,        repeat the calibration steps.

Sensitivity inputs can be added to the firmware as well so that the usercan adjust to be more or less sensitive from the calibrated values.

Another functionality which the tool with its on-board sensor array andsignal processing logic can deliver is a so-called ‘double blank’monitoring functionality, which is useful when magnetic coupling device10 is used to de-stack ferromagnetic sheet blanks or partially shapedsheet material components from a staple (e.g. for transfer of the blanksbetween or to a blank drawing or molding station). This functionalityincludes a calibration of the tool as follows:

-   -   1. Toggle the calibration input.        -   a. Now the user is in calibration mode.        -   b. Wait for the power LED to stop flashing.        -   c. Place the tool with its pole shoes on one sheet of steel            with ideal contact and turn on to an on state or            alternatively to a known partial on state the magnetic flux            source of the tool (Note: this step is required each time            the user changes sheet material thicknesses).    -   2. Toggle the calibration input.        -   a. Wait for the power LED to stop flashing.        -   b. Once the power LED stops flashing, turn off the unit.    -   3. Once the poser LED stops flashing, the tool will go back into        normal mode.

At this point in time, the state outputs of the tool should befunctioning properly. If this is not the case, repeat the calibrationsteps. If in a subsequent operation, the sensed leakage flux for thecalibrated on state or partial on state is less than the storedcalibrated value by a threshold amount (absolute or percentage) thentool 10 may be coupled to multiple workpieces instead of a singleworkpiece.

As mentioned herein other configurations of magnets may be used in placeof permanent magnets 30, 32. Referring to FIGS. 26-30 , an exemplaryswitchable permanent magnet assembly 200 of the present disclosure isrepresented. Switchable permanent magnet assembly 200 may replacemagnetic flux source 15. Further, permanent magnet assembly 200 isplaced in a non-ferrous housing, as opposed to housing 22 for magneticcoupling device 10. As explained in more detail herein pole portions 250of permanent magnet system 200 are located at a lower side of thehousing and contact workpiece 17 (see FIGS. 29 and 30 ) or have poleextension members positioned directly below pole portions 250 andcontacting workpiece 17.

Switchable permanent magnet assembly 200 includes an upper platter 212and a tower platter 214 to be placed in housing 22. Each of platters 212and 214 include a plurality of spaced-apart permanent magnets 230 and aplurality of pole portions 250. Each of the plurality of spaced-apartpermanent magnets 230 are illustratively shown as a single permanentmagnet, but may comprise multiple permanent magnets and/or at least onepermanent magnet positioned within a housing. Exemplary platters areprovided in U.S. Pat. No. 7,161,451, German Utility ModelDE202016006696U1, and U.S. Provisional Patent Application No.62/248,804, filed Oct. 30, 2015, titled MAGNETIC COUPLING DEVICE WITH AROTARY ACTUATION SYSTEM, docket MTI-0007-01-US-E, the entire disclosuresof which are expressly incorporated by reference herein.

Returning to the example of FIGS. 26-30 , each permanent magnet 230 hasa north pole side 232 and a south pole side 234. The permanent magnets230 and pole portions 250 of platter 212 and of platter 214 are eacharranged to form a closed shape wherein one of pole portions 250 ispositioned between two of permanent magnets 230. Further, they permanentmagnets 230 are arranged so that each of the two permanent magnets 230contacting the pole portion 250 therebetween have either their northpole sides or their south pole sides contacting the pole portion 250.When the north pole sides of the adjacent permanent magnets 230 arecontacting a pole portion 250, the pole portion 250 is referred to as anorth pole portion. When the south pole sides of the adjacent permanentmagnets 230 are contacting a pole portion 250, the pole portion 250 isreferred to as a south pole portion.

Each of upper platter 212 and lower platter 214 includes an equal andeven number of permanent magnet 230 and an equal number of pole portions250. In one embodiment, in each of upper platter 212 and lower platter214, permanent magnets 230 and pole portions 250 are arranged in acircular configuration.

In embodiments, lower platter 214, like magnet 30 in tool 10, is heldstationary relative to the housing containing lower platter 214 andupper platter 212, like magnet 32 in tool 10, rotates relative to lowerplatter 214. Upper platter 212 is rotatable in directions 290, 292 abouta central axis 294 relative to lower platter 214 to alter an alignmentof the permanent magnets 230 and pole portions 250 (if upper platter 212relative to the permanent magnets 230 and pole portions 250 of lowerplatter 214.

Switchable permanent magnet assembly 200 is considered to be on statewhen the south pole portions 250 of lower platter 214 are aligned withthe south pole portions 250 of upper platter 212 and the north poleportions 250 of lower platter 214 are aligned with the north poleportion 250 of upper platter 212. In the on-state, a workpiece is heldby magnetic coupling device 10 due to a completion of a magnetic circuitfrom the aligned north pole portions 250 of upper platter 212 and lowerplatter 214, through the workpiece, and to the aligned south poleportions 250 of upper platter 212 and 214.

Switchable permanent magnet assembly 200 is considered to be in an offstate when the south pole portions 250 of lower platter 214 are alignedwith the north pole portions 250 of upper platter 212 and the north poleportion 250 of lower platter 214 are aligned with the south poleportions 250 of upper platter 212. In the off state a workpiece is notheld by magnetic coupling device 10 due to a completion of a magneticcircuit within upper platter 212 and lower platter 214 from the alignednorth pole portions 250 of upper platter 212 to the south pole portions250 of lower platter 214 and from the aligned north pole portions ofupper platter 212 to the south pole portions 250 of lower platter 214.

Switchable permanent magnet assembly 200 is considered to be in apartial on state when the south pole portions 250 of upper platter 212are partially overlapping the north pole portions 250 of lower platter214 and the north pole portions 250 of upper platter 212 are partiallyoverlapping the south pole portions 250 of lower platter 214. When inthe partial on state, a workpiece may be held by magnetic couplingdevice 10 due to a completion of a magnetic circuit from the overlappingnorth pole portions 250 of upper platter 212 and lower platter 214,through the workplace 27 and to the overlapping south pole portions 250of upper platter 212 and lower platter 214. The strength of the magneticcircuit increases as the degree of overlap of the overlapping north poleportions 250 of upper platter 212 and lower platter 214 and theoverlapping south pole portions 250 of upper platter 212 and lowerplatter 214 increases.

Referring to FIG. 26 , upper platter 212 is illustrated. Upper platter212 includes a cylindrical base component 220 having a central aperture222 and a plurality of radially extending apertures 224. Each of theradially extending apertures 224 is sized and shaped to receive apermanent magnet 230. Each permanent magnet 230 has a north side 232, asouth side 234, a radially inward facing side 236, a radially outwardfacing side 238, a top 240, and a bottom.

Referring to FIG. 27 , a top view of upper platter 212 is shown.Cylindrical base component 220 surrounds each of north sides 232, southsides 234, radially inward facing side 136, and radially outward facingside 138 of permanent magnet 230. In one embodiment, apertures 224 arenot through apertures, but rather blind depth apertures from the bottomside of cylindrical base component 220 and hence cylindrical basecomponent 220 would also surround top 240 of pole portions 250. In theillustrated embodiment, cylindrical base component 220 is a singleintegral component. In one embodiment., cylindrical base component 220is comprised of two or more components joined together.

As shown in FIG. 27 , permanent magnets 230 are arranged so that thenorth sides 232 of adjacent magnets are facing each other and the southsides 234 of adjacent magnets 230 are facing each other. Thisarrangement results in the portions 250 of cylindrical base component220 between permanent magnet 230 to act as pole extensions for permanentmagnet 230. In embodiments, base component 220 and hence pole portions250 are made of steel. Other suitable ferromagnetic materials may beused for base component 220.

Referring to FIG. 28 , upper platter 212 is shown exploded relative tolower platter lower platter 214. Lower platter 214 is generallyidentical to upper platter 212. Upper platter 212 may be rotatedrelative to lower platter 214 to place switchable permanent magnetassembly 200 in an on state, a partial on state, or an off state.

Referring to FIG. 29 , upper platter 212 and lower platter 214 arearranged in an on-state wherein the south pole portions 250 of upperplatter 212 are adjacent the south pole portions 250 of lower platter214 and the north pole portions 250 of upper platter 212 are adjacentthe north pole portions 250 of lower platter 214. In the on-state, aworkpiece 27 being made from a ferromagnetic material is held bymagnetic coupling device including the upper and lower platters 212, 214due to a completion of a magnetic circuit from the aligned north poleportions 250 of upper platter 212 and lower platter 214, through theworkpiece 27, and to the aligned south pole portions 250 of upperplatter 212 and lower platter 214. The lower surfaces of north and southpole portions 250 form the workplace contact interfaces. Alternatively,instances of pole shoes 38, although of different shape than in FIG. 1 ,may positioned between the lower surfaces of north and south poleportions 250 and the workpiece 17 to provide the workplace contactinterfaces 44 with workplace 17. Further, sensors 98 may be positionedadjacent various ones of north pole and south pole portions 250. Inembodiments, at least one of the north pole portions 250 and at leastone of the south pole portions 250 has a sensor 98 associated therewithto monitor the leakage flux associated with the respective north poleportion and the respective south pole portion. As shown in FIG. 27 , afirst sensor 98 may be placed proximate to a north pole portion 250,such as directly over north pole portion 250 or radially outward ofnorth pole portion 250, and a second sensor 98 may be placed proximateto a south pole portion 250, such as directly over south pole portion250 or radially outward of south pole portion 250. Logic control circuit23 may perform calibration runs for permanent magnet assembly 200 in asimilar fashion as described herein for magnetic coupling device 10 tostore sensor values for determining operating states of the deviceincluding permanent magnet assembly 200.

Referring to FIG. 30 , upper platter 212 and tower platter 214 arearranged in an off-state when the south pole portions 250 of upperplatter 212 are adjacent the north pole portions 250 of lower platter214 and the north pole portions 250 of upper platter 212 are adjacentthe south pole portions 250 of lower platter 214. In the off-state, aworkpiece 27 being made from a ferromagnetic material is not held bymagnetic coupling device in the upper and lower platters 212, 214 due toa completion of a magnetic circuit between the aligned south poleportions 250 of upper platter 212 and the north pole portions 250 oflower platter 214 and between the aligned north pole portions 250 ofupper platter 212 and the south pole portions 250 of lower platter 214.In other words, platters 212 and 214 shunt the magnetic circuit withinthe pole portions 150 causing the external magnetic field to collapse.Upper platter 212 and lower platter 214 may also be arranged to provideone or more partial on states of the magnetic coupling device includingupper platter 212 and lower platter 214.

As mentioned herein other configurations of magnets may be used in placeof permanent magnets 30, 32. Referring to FIGS. 31-33 , an exemplaryswitchable permanent magnet assembly 300 of the present disclosure isrepresented. Switchable permanent magnet assembly 300 may replacemagnetic flux source 15. Further, permanent magnet assembly 300 isplaced in a non-ferrous housing, as opposed to housing 22 for magneticcoupling device 10. As explained in more detail herein pole portions 350of permanent magnet system 300 are located at a lower side of thehousing and contact workpiece 17 or have pole extension members 340 (seeFIGS. 31-33 ) positioned directly below pole portions 350 and contactingworkpiece 17.

Switchable permanent magnet assembly 300 includes an upper assembly 312and a lower assembly 314. Each of assemblies 312 and 314 include aplurality of spaced-apart permanent magnets 330 and a plurality of poleportions 350. Each of the plurality of spaced-apart permanent magnets330 are illustratively shown as a single permanent magnet, but maycomprise multiple permanent magnets and/or at least one permanent magnetpositioned within a housing.

Each permanent magnet 330 has a north note side (N) and a south poleside (S). The permanent magnets 330 and pole portions 350 of assembly312 and of assembly 314 are each arranged in a linear array wherein oneof pole portions 350 is positioned between two of permanent magnets 330.Further, the permanent magnets 330 are arranged so that each of the twopermanent magnets 330 contacting the pole portion 350 therebetween haveeither their north pole sides (N) or their south pole sides (S)contacting the pole portion 350. When the north pole sides (N) of theadjacent permanent magnets 330 are contacting a pole portion 350, thepole portion 350 is referred to as a north pole portion. When the southpole sides (S) of the adjacent permanent magnets 330 are contacting apole portion 350, the pole portion 350 is referred to as a south poleportion.

In embodiments, tower assembly 314, like magnet 30 in tool 10, is heldstationary relative to the housing containing lower assembly 314 andupper assembly 312, like magnet 32 in tool 10, rotates relative to lowerassembly 314. Upper assembly 312 is translatable relative to lowerassembly 314 in directions 390 and 392 to alter an alignment of thepermanent magnets 330 and pole portions 350 of upper assembly 312relative to the permanent magnets 330 and pole portions 350 of lowerassembly 314. Permanent magnets 330 of lower assembly 312 are spacedapart from workpiece 17 due to pole shoes 340 coupled to pole portions350. Alternatively, pole portions may be extended to provide thespacing. Additionally, a spacer (not shown) is provided between thepermanent magnets of upper assembly 312 and lower assembly 314.

Switchable permanent magnet assembly 300 is considered to be in an onstate when the south pole portions 350 of lower assembly 314 are alignedwith the south pole portions 350 of upper assembly 312 and the northpole portions 350 of lower assembly 314 are aligned with the north poleportions 350 of upper assembly 312 (see FIG. 20 ). In the on-state,workpiece 17 is held by switchable permanent magnet assembly 300 due toa completion of a magnetic circuit from the aligned north pole portions350 of upper assembly 312 and lower assembly 314, through the workpiece27, and to the aligned south pole portions 350 of upper assembly 312 andlower assembly 314.

Switchable permanent magnet assembly 300 is considered to be in an offstate when the south pole portions 350 of lower assembly 314 are alignedwith the north pole portions 350 of upper assembly 312 and the northpole portions 350 of lower assembly 314 are aligned with the south poleportions 350 of upper assembly 312 (see FIG. 22 ). In the off state, aworkpiece 17 is not held by switchable permanent magnet assembly 300 dueto a completion of a magnetic circuit within upper assembly 312 andlower assembly 314 from the aligned north pole portions 350 of upperassembly 312 to the south pole portions 350 of lower assembly 314 andfrom the aligned north pole portions of upper assembly 312 to the southode portions 350 of lower assembly 314.

Switchable permanent magnet assembly 300 is considered to be in apartial on state when the south pole portions 350 of upper assembly 312are partially overlapping the north pole portions 350 of lower assembly314 and the north pole portions 350 of upper assembly 312 are partiallyoverlapping the south pole portions 350 of lower assembly 314. When inthe partial on state, a workpiece 17 may be held by switchable permanentmagnet assembly 300 due to a completion of a magnetic circuit from theoverlapping north pole portions 350 of upper assembly 312 and lowerassembly 314, through the workpiece 17, and to the overlapping southpole portions 350 of upper assembly 312 and lower assembly 314. Thestrength of the magnetic circuit increases as the deoree of overlap ofthe overlapping north pole portions 350 of upper assembly 312 and lowerassembly 314 and the overlapping south pole portions 350 of upperassembly 312 and lower assembly 314 increases.

Further, sensors 98 may be positioned adjacent various ones of northpole and south pole portions 350. In embodiments, at least one of thenorth pole portions 350 and at least one of the south pole portions 350has a sensor 98 associated therewith to monitor the leakage fluxassociated with the respective north pole portion and the respectivesouth pole position. As shown in FIG. 31 , a first sensor 98 may beplaced proximate to a north pole portion 350, such as directly overnorth pole portion 350 or radially outward of north pole portion 350,and a second sensor 98 may be placed proximate to a south pole portion350, such as directly over south pole portion 350 or radially outward ofsouth pole portion 350. Logic control circuit 23 may perform calibrationruns for permanent magnet assembly 300 in a similar fashion as describedherein for magnetic coupling device 10 to store sensor values fordetermining operating states of the device including permanent magnetassembly 200.

Referring to FIGS. 8-12 , in embodiments, magnetic coupling tool 10includes degaussing functionality for removing residual magnetismfollowing handling of workpieces using magnetic coupling tool 10.Additional details regarding systems providing degaussing functionalityare provided in US Provisional Patent Application No. 62/490,706, titledMAGNETlC COUPLING TOOL WITH DEGAUSS CAPABILITY, filed Apr. 27, 2017, theentire disclosure of which are expressly incorporated by referenceherein.

In an exemplary embodiment, magnetic coupling device 10 includes anon-off switchable di-pole magnetic flux source 15; a first housingcomponent 22 in which is received the magnetic flux source 15; and, apair of magnetic pole extension shoes 38 having each a workpieceengagement surface 44. The pole extension shoes 38 are mounted to thefirst housing component 22 such as to receive magnetic flux from themagnetic flux source 15 and make such available at the workpieceengagement surfaces 44. At least one magnetic field sensors 98, butpreferably a number of first magnetic field detection sensors equal innumber to the number of pole extension shoes and/or workpiece engagementsurfaces, are located a predetermined distance away but in closeproximity to a flux detection surface 46 preferably at an end oppositethe workpiece engagement surface 44 of an associated one of the poleextension shoes. A pair of degaussing electrical windings 110, one eachwound about a section of an associated one of the two magnetic poleextension shoes 38, are provided. Logic control circuit 23 is furtheroperative to (i) receive an output signal from the at least an onemagnetic field detection sensor and determine from said output signal(s)an operating state of the tool indicative of the magnetic flux sourcebeing switched off, (ii) in such event switch-on an electric powersupply to the degaussing electrical windings and (iii) perform adegaussing cycle wherein the degaussing electrical windings generate anoscillating and alternating magnetic field over a predetermined time.

In embodiments, the degaussing electrical windings 110 and exchangeablepole extension shoe members 38 form modular units attachable to thefirst housing component 29, wherein the pole extension shoe members 38form part of a magnetic flux delivery circuit of the EOAMT 10 when usedin magnetically coupling the EOAMT 10 with a workpiece 17, as well as,form part with the degaussing windings 110 of an electromagnet which isoperated in a degaussing cycle during degaussing of the workplace 17.

In embodiments, the logic control circuit 23 is devised such that thedegaussing cycle will be performed immediately before magnetic couplingdevice 10 is removed from a workpiece 17 that has previously beenhandled with magnetic coupling device 10, i.e. when magnetic couplingdevice 10 is stationary with the workpiece engagement surfaces 44 at theworkpiece 17 and the magnetic flux source 15 has been turned off toeffect decoupling. By performing the degaussing cycle at that stage, thepole shoes 38 of magnetic coupling device 10 will act as conduits tofocus the degaussing operation to the workpiece area which in the firstplace will exhibit the magnetic remanence after placing magneticcoupling device 40 in the off state.

In embodiments: the pole extension shoes 36 are comprised of at leasttwo components, a first pole extension member 38 a secured in removablemanner to the first housing component and a second pole extension member38 b removably secured in extension to the first member and defining theworkpiece engagement surface 44, wherein the degaussing electricalwindings 110 encircle a section of the second pole extension member 38b. This two-part pole shoe lay out enables the EOAMT 10 to be deployedwith or without degaussing functionality, by allowing simple decouplingof the second pole extension member 38 b from the first pole extensionmember 38 a, whereby the first pole shoe member 38 a will thenexhibit/provide the workpiece engagement surface 44. Equally, it allowsthe second pole shoe member 38 b to be exchangeable so as to provide aworkpiece engagement surface 44 that it optimized to the geometry of theworkplace 17.

In embodiments, the pole shoes 38 have, in the section covered by thedegaussing windings 110, a cross section sufficient to direct asubstantial and preferably all of the magnetic flux generated upon thedegaussing windings 110 being energized, to the workpiece engagementsurface 44. This ensures that all of the magnetic flux provided by thedegaussing windings 110 is effectively used in performing degaussing ofthe workpiece 17 at the contact zone with the pole extension shoes 38.It is of course also possible for the pole shoes 38 to have in thesection covered by the degaussing windings 110, a cross sectionsufficient to direct a substantial portion (but not an) of the magneticflux generated upon being energized, to the workpiece engagement surface44 and generate magnetic flux leakage around the workpiece engagementsurface 44. This measure will assist in degaussing zones outside theimmediate contact zone between pole extension shoes and workplace.

In embodiments, the logic control circuit 23 further includes an ACdriver (hardware or software) for generating a pulse width modulated(PWM) current which as explained in mere detail herein is supplied tothe degaussing windings 110. Further, in embodiments, functional blocksof the logic control circuit 23 for performing the degaussing cycle.

In embodiments, the degaussing windings 110, in being wrapped about(i.e. encircling) a section of the ferromagnetic pole extension shoes38, effectively create an electromagnet. The control circuit and themicroprocessor of logic control circuit 23 are configured such that theelectromagnets are driven to alternate the polarity and magnitudebeneath the poles shoes 38. The pole shoes 38 always have their fieldsin opposite directions during normal (coupling) use of the tool. Fordifferent size tools the parameters of the electromagnets are changed tocorrelate the strength of the magnetic field to that of the switchablepermanent magnet unit deployed in the magnetic coupling device 10 toovercome the residual magnetic field that is left in the workpiecewithout creating a new residual field.

The two electromagnets performing the degaussing function can becontrolled using a typical DC motor driver. In order to minimize theresidual magnetism left in the workpiece 17, an alternating magneticfield that decreases in magnitude is used. The alternating magneticfield is controlled by the microcontroller (through the dedicated DCmotor drive chip) with a pulse width modulated (PWM) waveform and adirection pin. The direction pin is what alternates the direction of thecurrent supplied to the degaussing windings (coils). The PWM waveform iswhat controls the actual magnetic field seen through the electromagnets.

There are a number of parameters that affect the PWM waveform, and inturn, the magnetic field, such as frequency, duty cycle, and amplitudesworkpieces 17 with different geometries and steel compositions requiredifferent parameters to properly degauss. Therefore, the control circuitcan either be provided with suitable memory banks for storingpre-defined parameter tables accessible to the programmedmicroprocessor, or alternatively customized data can be stored which issampled during calibration runs during which the parameters are cycledand changed, the residual magnetism of the workpiece measured and thenan ‘optimal’ set of parameters for a PWM waveform determined, thatachieves a desired degaussing level of the specific workpiece. Exemplaryhardware circuits for achieving various forms of PWM drivers areprovided in U.S. Pat. Nos. 3,895,270 and 4,384,313, although moregeneric circuits coupled to a programmable microprocessor may also beemployed.

Turning to the Figures exemplary embodiments are illustrated. Referringto FIGS. 8-11 , an exemplary embodiment of magnetic coupling device 10including degaussing functionality is illustrated. Pole shoes 38 includedegaussing windings 110 wrapped around each pole shoe 38.

Multi-piece ferromagnetic pole extension shoes 38 are provided. Poleshoes 38 are mounted to the width-ward recessed sides at the lowerportion of housing 22 using a pair of fastening screws 40. Pole shoes 38include an essentially rectangular prismatic first member 38 a havingchamfered edges along its height, which are mounted to the width-wardsides at the lower portion of housing 22 and complement the shape of theupper portion of housing 22, and a rectangular plate-like second member38 b secured by fastening screws 38 c at the lower terminal ends ofupright shoe member 38 a. Alternative shapes of pole shoes 38′ may beused.

The pole extension shoes 38 define at a lower face (i.e. at the secondmember 38 b) respective workpiece engagement surfaces 44 which in theillustrated embodiment are planar, but could be of different geometryand/or contoured to form fittingly abut against a curved or uneventarget surface of a workpiece to be magnetically coupled to and handledby tool 10. The fit of pole shoes members 38 a to the receptaclesdefined at the lower portion of housing 22 is such as to minimize orindeed essentially avoid magnetic circuit air gaps in other words, thethick-walled width-ward portions of housing 22 and the pole shoes 38′together form a magnetic flux path from the magnets 30, 32 to the topaxial end faces of housing 22 and the lower end of pole shoes 38.

Referring to FIG. 11 , an exploded view of degauss assembly 110 isillustrated. Degauss assembly 110 includes en electric degaussingwinding or coil 114 wound about a bobbin 112, with a 2-wire ribbon cable116 for connection to a control circuit as will be explained below. Coil114 and bobbin 112 are received within top bobbin cover 118 made ofnon-ferromagnetic sleet or other material, whereby ribbon cable 116passes through an opening in the top wall of bobbin cover 118. Bottombobbin cover 120 is then fastened to top bobbin cover 118 via fasteners122.

The above mentioned pole extension shoe 38 of the switchable permanentmagnet unit 20 is then incorporated into the degaussing module bysliding rectangular prismatic pole shoe component 38 a through anappropriately and correspondingly shaped opening in the middle of bottombobbin cover 120 to extend through bobbin 112 and protrude past thecomplementary opening in top bobbin cover 118. The customizable poleextension shoe component 38 b, which provides the workpiece engagementsurface 44, is either already attached to the lower axial end of poleshoe component 38 a using fasteners 38 c, or can be secured afterwards,and comes to abut against the lower bobbin cover plate 120. Aspreviously noted, pole extension shoe component 38 a and degaussing coil114 effectively provide a dedicated electromagnet for performing thedegaussing cycle.

Now referencing FIG. 10 , each 2-wire ribbon cable 116 is routed throughdedicated degauss wire routing bores 124 extending through the upperportion of housing 22 on either width and side of cylindrical bore 24,and the two degauss modules 110 are then attached to housing 22 ofswitchable magnet unit 20 through the above mentioned fastening bolts40, thus also securing the pole extension shoes 38 to the unit 22 andthus providing for completion of the switchable magnetic flux sourceused in normal operation of the tool 10 to attach to a workpiece.

The logic control circuit 23, in particular main PCB 92 incorporates thenecessary hardware and software required for operating the degaussmodules 110, in particular for generating the degaussing AC (andcontrolling its waveform) that is sent through the degaussing coils 114.The 2-wire ribbon cables 116 of degaussing modules 110 attach to socketsat pole board PCB 94 which is connected to main control board PCB 92 viaboard-to-board connectors 102, 104.

Current (which given it is PWM-modulated can appropriately also bedescribed as an operating signal for the degaussing coils 114) goingthrough the ribbon cables 116 to the coils 114 is controlled via themicrocontroller and a motor driver on the main control PCB 92. Thesesignals are controlled via a PWM waveform from the microcontroller toprovide a high frequency AC signal. The degaussing PWM and direction pinwork by alternating positive/negative between the North and South polesand decreasing the magnitude each period. Depending on the materialcomposition and geometry of the workpiece being degaussed, differentwaveform parameters need to be changed including, but not limited to,frequency, magnitude, and shape.

The PWM signals effectively create a rapidly changing magneticdegaussing circuit with the workpiece which eliminates the residualmagnetism. Exemplary processes are disclosed herein.

As regards degaussing coils 114, the wire gage, length, and number ofwindings (as well as how far those winding are from the pole extensionshoe (or core of the electromagnet) of the coil affect the inductanceand resistance of the coils. The changes in inductance and resistanceaffect the ramp up time of the coils, which means different coils(different size units) need different series of PWM waveforms. The idealramp up time can be calculated to determine the appropriate frequency.In general, larger degaussing units require more coil mass, whichincreases the ramp up time meaning that larger units will take longer todegauss.

The way the coils are wired also has an effect on the inductance andresistance of the coils. If the coils are wired in series the resistanceis roughly double that of when they are in parallel. Thus, the way thecoils are wired also has an effect on the PWM waveform.

In embodiments, five parameters are used by the logic control circuit 23to alter the operation of degaussing coils 114. These parameters include(a) Prescaler. The prescaler divides the counter dock frequency from themain clock of the main PCB board's STM32F030R8T6. 240 has been thestandard used for consistency (when the period is set to 200 thefrequency for each pulse is 1 kHz); (b) Period: The period for eachindividual pulse (positive integer with 1 unit=5 μs when prescaler setto 240): (c) Steps: The number of pulses at each amplitude (positiveinteger); (d) Cycles: The number of amplitudes used to degauss (positiveinteger); and (e) Amplitude: The maximum duty cycle used to degauss(float with 0<x<1).

An exemplary degauss waveform is shown in FIG. 12 . It should be notedthough that the step function could be replaced with other type offunctions that seek to mimic a sine wave form more closely. Thefollowing is the list of parameters used to create the waveform of FIG.12 : (a) Period: 10 (1 time unit on this graph=5 μs when the prescaleris set to 240); (b) Steps: 3 (Note that there are 3 positive steps and 3negative steps per cycle); (c) Cycles: 3 (Note that waveform goespositive and then negative a total of 3 times. Further note that thenumber of cycles is equivalent to the number of different magnitudes)(d) Amplitude: 0.9 (Note that the maximum duty cycle is 0.9 and that theaverage waveform magnitude is equal to the duty cycle/amplitude. Furthernote that the magnitudes are determined from the maximum amplitudedivided by the number of cycles 0.9/3=0.3 (1st Cycle=±0.2nd Cycle=±0.6;and 3rd Cycle=±0.3)).

By performing calibration runs in varying the above parameters, thedegaussing efficiency and efficacy of magnetic coupling tool 10 may beoptimized. For example, the table below was prepared using data obtainedusing a prototype coupling tool with degauss functionality based on aMagswitch AR70 unit. The table compares the performance of differentsoftware parameters and the maximum residual gauss level observed. Thisdata was taken on 51200 steel, which is known to retain residualmagnetism. This data was taken with the prescaler set to 240.

TABLE 1 AR70 Degauss Data on 51200 Steel Test Period Max Residual # (1unit = 5 μs) Steps Cycles Amplitude Observed (G) 1 400 100 5 0.95 12 2400 50 10 0.95 17 3 400 50 5 0.95 15

The number of steps per cycle was double the amount for the 1^(st) testas compared to the 2^(nd) and 3^(rd) tests. The first test had a lowerresidual, thus the ramp up for the 2^(nd) and 3^(rd) test was not longenough (the number of steps, directly relates to the ramp up).

Using a different type of magnetic flux unit, a Magswitch J50 unit withdegauss capability, different tests were conducted which show theimportance of running calibration tests in determining the bestdegaussing outcomes for given workpiece.

The following software parameters were used in the generation of a PWMsignal supplied to the degaussing coils: Prescaler: 240; Period: 250;Steps: 10; Cycles: 20; and Amplitude: 0.7. With these parameters, thedegauss cycle took roughly 200 ms, and the maximum current draw of thecoils was about 0.9 A. The coils were wired in parallel for this unit.The total resistance of the coils was roughly 8 Ω.

With a change of parameters, different outcomes are observable. Thefollowing software parameters were used in the generation of a PWMsupplied to the degaussing cells for a second test: Prescaler: 240;Period: 300; Steps: 10; Cycles: 20; and Amplitude: 0.7. With theseparameters, the degauss cycle takes roughly 200 ms, and the maximumcurrent draw was about 0.3 A. The coils are wired in series for thisunit. The total resistance of the coils was roughly 30 Ω.

A number of other parameters were tested before narrowing these down.Initially, the number of steps was much greater, but it was creating amore sustained magnetic field that had negative effects on degaussing.The number of cycles was initially much lower, but with a decreasednumber of steps, the number of cycles could be increased while keepingthe degauss cycle under 0.5 s. The amplitude was initially higher, butwith the increased frequency on this unit, there were issues with thelimits of the transistor switching speeds.

It will be understood that the above provided data is based prototypedevelopment and optimization will yield degaussing cycle times that areacceptable in robotic handling of workpieces.

Referring to FIG. 24 , a functional processing sequence 600 of logiccontrol circuit 23 is illustrated. The processing sequence shows thevarious steps which the tool's software is programmed to undertake inemploying an initial four calibration process of the tool (as comparedto the 3-step outline above) for a given workpiece 17, and the stepsperformed in determining the various possible status of the tool in itsmagnetic interaction with the workpiece 17, based on comparison ofactual sensor data with calibrated threshold sensor data (averaged). Thetool 10 executes a startup routine, as represented by block 602. A checkis made to see if a degauss input of the input devices 41 was triggered,as represented by block 604. If triggered a check is made to determineif the magnetic flux source 15 is in an off state as represented byblock 606. If so, a degauss cycle is performed as represented by block608.

If the degauss input was not triggered, a check is made to determine ifa calibration input of the input devices 41 was triggered, asrepresented by block 610. It so, a four step calibration run isperformed, as represented by block 612. In one example, magneticcoupling device 10 is calibrated to a single sheet thickness (1 mm) thatis a small square (100 mm×100 mm). The two Limiting Positions arecalibrated for positions of magnetic coupling device 10 near the centerof the sheet. The North pole signal is calibrated for the north poleshoe being on an edge of the sheet (not in the corners) and the Southpole signal is calibrated for the south pole shoe being on an edge ofthe sheet (not in the corners).

If the calibration input was not triggered, the sensor values formagnetic sensors 98 are averaged, as represented by block 614. In oneexample, block 614 entails for each sensor 98 averaging the magneticfield sensor values of the tool sampling magnetic flux data pointswithin a defined (very short) measurement time period, and processingthese signals by the on-board processor of the magnetic field sensor andsensor signal processing circuit unit, all of which can be performed ina few milliseconds. This of course increases accuracy of data samplingand performance of the tool's sensor suite to determine the differenttool status.

A check is made to see if the sampled values indicate that the magneticflux unit 15 is in an on state (or calibrated partial on state), asrepresented by block 616. If not, it is determined the magnetic fluxcircuit is off, as represented by block 618. If so, the magnetic fluxcircuit is indicated to be on, as represented by block 620.

Next, the averaged sensor values for the magnetic sensor associated withthe north pole shoe and the sensor values for the magnetic sensorassociated with the south pole are checked to see it is within the rangeof the limiting position 1 and limiting position 2 calibrated values, asrepresented by block 622. On the small thin plate mentioned above, themagnetic flux sensor values will start to change rapidly as the magneticcoupling device is moved away from the center of the plate. If both arein range, it is determined that a part is present and engaged in atargeted zone, as represented by block 624. If not, a check of themagnetic flux sensor values for each magnetic sensor 98 is compared tothe respective pole position calibration values to determine if eitherthe north pole or the south pole is on the part, as represented byblocks 626-638.

In one embodiment, a six step calibration procedure is implemented. Thefollowing sensor values are calibrated: (1) Limiting position 1 Northbest flux circuit; (2) Limiting position 1 South best flux circuit; (3)Limiting position 2 North worst flux circuit; (4) Limiting position 2South worst flux circuit; (5) South pole position; and (6) North poleposition. This calibration procedure differs from the four stepcalibration sequence above wherein the limit positions corresponded tothe center of the sheet. In this procedure, the magnetic coupling device10 is within the limit ranges as long as both the north pole shoe andthe south pole shoe are on the sheet. For sensor values (1) and (2), themagnetic coupling device 10 is located at the center of the sheet, andthese values are recorded. For sensor value (3), the magnetic couplingdevice 10 is located with the north pole shoe adjacent to two edges ofthe sheet (in a corner) and the value for the north pole, shoe sensor isrecorded. For sensor value (4), the magnetic coupling device 10 islocated with the south pole shoe adjacent to two edges of the sheet (ina corner) and the value for the south pole shoe sensor is recorded.Sensor values (5) and (6) are the same as sensor values (3) and (4) forone example (limit range is whole sheet). If the sensor values for (3)and (4) where for positions not in the corners of the sheet, then sensorvalues (5)_ and (6) would differ from (3) and (4) because sensor values(5) and (6) are taken with magnetic coupling device in the corners ofthe sheet. Referring to FIG. 25 , an exemplary robotic system 700 isillustrated. The embodiments described in relation to robotic system 700may be applied to other types of machines, (e.g., mechanical gantries,crane hoists, pick and place machines, etc).

Robotic system 700 includes electronic controller 770. Electroniccontroller 770 includes additional logic stored in associated memory 774for execution by processor 772. A robotic movement module 712 isincluded which controls the movements of a robotic arm 704. In theillustrated embodiment, robotic arm 704 includes a first arm segment 108which is rotatable relative to a base about a vertical axis. First armsegment 706 is moveably coupled to a second arm segment 708 through afirst joint 710 whereat second arm segment 708 may be rotated relativeto first arm segment 706 in a first direction. Second arm segment 708 ismoveably coupled to a third arm segment 711 through a second joint 712whereat third arm segment 711 may be rotated relative to second armsegment 708 in a second direction. Third arm segment 711 is moveablycoupled to a fourth arm segment 714 through a third joint 716 whereatfourth arm segment 714 may be rotated relative to third arm segment 711in a third direction and a rotary joint 718 whereby an orientation offourth arm segment 714 relative to third arm segment 711 may be altered.Magnetic coupling device 10 is illustratively shown secured to the endof robotic arm 704. Magnetic coupling device 10 is used to couple aworkpiece 17 (not shown) to robotic arm 704. Although magnetic couplingdevice 10 is illustrated, any of the magnetic coupling devices describedherein and any number of the magnetic coupling devices described hereinmay be used with robotic system 700.

In one embodiment, electronic controller 710 by processor 772 executingrobotic movement module 702 moves robotic arm 704 to a first posewhereat magnetic coupling device 100 contacts the workpiece at a firstlocation. Electronic controller 770 by processor 772 executing amagnetic coupler state module 776 instructs magnetic device 10 to moveupper magnet 32 relative to lower magnet 30 to place magnetic couplingdevice 10 in one of the on state or a partial on state to couple theworkplace to robotic system 700. In embodiments, magnetic coupler statemodule 776 includes the functionality of logic control circuit 23. Thus,the functionality of logic control circuit 23 may be located within tool10 or remote from tool 10. Electronic controller 770 by processor 772executing robotic movement module 702 moves the workpiece from the firstlocation to a second, desired, spaced apart location. Once the workpieceis at the desired second location, electronic controller 770 byprocessor 772 executing magnetic coupler state module 776 instructsmagnetic device 10 to move upper magnet 12 relative, to lower magnet 14to place magnetic coupling, device 10 in the off state to decouple theworkpiece from robotic system 700. Electronic controller 770 thenrepeats the process to couple, move, and decouple another workpiece 17.In one embodiment, prior to moving away from the workpiece 17,controller 770 instructs magnetic coupling device 10 to execute adegauss cycle.

In embodiments, magnetic coupling device 10 has an elongated housing tohold multiple instances of magnetic flux source 15 in a linear array. Anexemplary device having multiple instances of magnetic flux sources 15is the LAY Series unit as manufactured and sold by Magswitch TechnologyInc. Referring to FIGS. 34 and 35 , a magnetic coupling device 400 isshown. Magnetic coupling device 400 includes a housing 402 containingmultiple instances of magnetic flux source 15, illustratively fluxsources 15A-C. Pole extension shoes 404 are provided along a lower sideof housing 402. The relative positions of magnet 32 of each instance ofmagnetic flux source 15 is controlled through an actuator 406. Eachinstance of magnetic flux source 15 operates in the same manner as formagnetic coupling device 10 and are placable in any one of an on state,an off state, and a partial on state.

Further, magnetic coupling device 400 includes magnetic field sensors 98positioned within housing 402. Magnetic field sensors 98 are shown beingpositioned proximate the pole shoes 404 of two of the magnetic fluxsources 15, illustratively flux sources 15A and 15C. In embodiments,magnetic field sensors 98 are associated with only a single flux source15 of the plurality of magnetic flux sources 15A-C. In embodiments,magnetic field sensors 98 are associated with each flux source 15 of theplurality of magnetic flux sources 15A-C. Logic control circuit 23 bymonitoring the magnetic field sensors 98, is able to determine a qualityof magnetic circuit formed by workpiece engagement surfaces 444 of poleshoes 404 and a workpiece 17, proximity to a workpiece 17, or otheroperating states disclosed herein.

In embodiments, magnetic coupling device 10 has an elongated housing tohold multiple instances of magnetic flux source 15 in a circular array.An exemplary device having multiple instances of magnetic flux source 15is the AY Series unit as manufactured and sold by Magswitch TechnologyInc. Referring to FIGS. 36 and 37 , a magnetic coupling device 450 isshown. Magnetic coupling device 450 includes a housing 452 supportingmultiple instances of magnetic flux source 15, illustratively fluxsources 15A-F, each having its own pair of workpiece engagement surfaces454. The relative position of magnet 32 for each instance of magneticflux source 15 is controlled through an actuator 458. Each instance ofmagnetic flux source 15 operates to form magnetic working circuitstherebetween through workpiece 17. The operation of magnetic couplingdevice 450 is described in more detail in U.S. Pat. No. 9,484,137, theentire disclosure of which is expressly incorporated by reference.

Further, magnetic coupling device 450 includes magnetic field sensors 98positioned within housing 452. In embodiments, magnetic field sensors 98are positioned in cylindrical protrusions 458 extending down from alower surface 460 of housing 452. In the illustrated embodiment, twomagnetic sensors 98 are positioned in respective protrusions 458, onebeing positioned between magnetic flux source 15F and 15A and the otherpositioned between magnetic flux sources 15C and 15D. In embodiments, amagnetic field sensor 98 is positioned in a protrusion 458 between anytwo of magnetic flux sources. In embodiments, magnetic field sensors 98are positioned in respective protrusions between each pair of adjacentmagnetic flux sources 15A-F along a diameter of the circular array.Logic control circuit 23 by monitoring the magnetic field sensors 98, isable to determine a quality of magnetic circuit formed by workpieceengagement surfaces 454 of magnetic flux sources 15A-F and workpiece 17,proximity to a workplace 17, or other operating states disclosed herein.

Various modifications and additions can be made to the exemplaryembodiments discussed without departing from the scope of the presentinvention. For example, while the embodiments described above refer toparticular features, the scope of this invention also includesembodiments having different combinations of features and embodimentsthat do not include all of the described features. Accordingly, thescope of the present invention is intended to embrace all suchalternatives, modifications, and variations as fall within the scope ofthe claims, together with all equivalents thereof.

1-69. (canceled)
 70. An end of arm magnetic coupling tool (EOAMT)devised for magnetically securing a ferromagnetic workpiece to a workingface of the tool, comprising: i) an on-off switchable magnetic fluxsource; ii) a housing component in which is received the magnetic fluxsource; iii) at least two, magnetic pole extension shoes having each aworkpiece engagement surface and flux detection surface at an endopposite to the workpiece engagement surface, wherein the pole extensionshoes are mounted to or at least partially form integral part of thehousing component such as to receive magnetic flux from the magneticflux source and make such available at the workpiece engagement surface;iv) a number of first magnetic field detection sensors equal in numberto the pole extension shoes and each located a predetermined distanceaway but in close proximity to the flux detection surface of anassociated one of the pole extension shoes; and v) a logic controlcircuit operative to receive an output signal from one or more of themagnetic field detection sensors and determine from said outputsignal(s) at least one of the following operating states of the tool:whether the magnetic flux source is switched on or off, whether there isa ferromagnetic workpiece in spatial proximity to one or more of theworkpiece engagement surfaces at the pole extension shoes, whether oneor more of the workpiece engagement surfaces at the pole extension shoesabut a workpiece, and whether abutment of a workpiece at one or more ofthe workpiece engagement surfaces is adequate and within predeterminedpositional thresholds.
 71. The EOAMT of claim 70, wherein the firstmagnetic field sensors and the logic control circuit are housed within afurther (second) housing component which is preferably of multi-piececonstruction and which is secured to the first housing component, suchas to provide a compact-footprint EOAMT with integrated magnetic fielddetection and workpiece-tool interface detection capabilities.
 72. TheEOAMT of claim 70, wherein the magnetic flux source, the first housingcomponent and the pole extension shoes are comprised in an on-offswitchable, dipole permanent magnet unit.
 73. The EOAMT of claim 72,wherein the first housing component is a ferromagnetic steel housingcomponent with a central cylindrical bore in which two cylindrical,diametrically polarized rare-earth permanent magnets are stacked suchthat one of the magnets is fixed against rotating within the cylindricalbore while the other magnet is free to rotate upon external torqueapplication by an actuator (pneumatic, hydraulic or electric) interfacedwith the rotatable magnet.
 74. The EOAMT of claim 72, wherein thathousing component comprises an upper, un-recessed portion and a lowerrecessed portion at which cuboid pole shoes are mounted such as to forma continuous, substantially air-gap-free flux delivery path towards theworkpiece engagement surfaces provided at the free axial terminal endsof the pole shoes, and wherein the flux detection surfaces opposite theworkpiece engagement surfaces are provided at an upper terminal face ofthe un-recessed housing portion, the housing having a substantiallyrectangular foot print.
 75. The EOAMT of claim 70, wherein a secondhousing component is provided in addition to the first housingcomponent, secured to an end of the first housing component opposite theworkpiece engagement surfaces.
 76. The EOAMT of claim 75, wherein thesecond housing component is substantially non-ferromagnetic and includesat least two passage ways extending preferably to terminal openingslocated opposite the flux detection surfaces at the first housingcomponent and receiving a respective one of two said first magneticfield detection sensors.
 77. The EOAMT of claim 75, wherein the secondhousing component houses an actuator which interfaces with the rotatablemagnet received in the first housing component to switch the magneticflux source “on” and “off”.
 78. The EOAMT of claim 70, wherein the logiccontrol circuit operative to receive output signals from the one or moreof the first magnetic field (and any additional) detection sensors anddetermine from said output signal(s) one or more of the operating statesof the tool, comprises a central control board, preferably a printedcircuit board which contains a pre-programmed or programmablemicroprocessor, with analog to digital converters (ADCs) for sensorsignal sampling and optionally with conditioning functionality.
 79. TheEOAMT of claim 78, wherein the logic control circuit of the centralcontrol board comprises additional transistors for interfacing a GPIO(general-purpose input/output) of the processor to industrial 24V logic.80. The EOAMT of claim 79, wherein the central control board furthercomprises power conditioning to take 24 V from an industrial powersupply and regulate it to 5V and/or 3.3 V for use by the microprocessorand other circuit components, as well as provide the working voltage forthe magnetic field sensors.
 81. The EOAMT of claim 78, wherein thecentral control board comprises a series of blank headers for accept acommunications module that allows the control board to interface withexternal control electronics.
 82. The EOAMT of claim 70, wherein thefirst magnetic field sensors are vector magnetometers, in particularsolid-state linear Hall Effect sensors or magneto resistive sensors,with very small form factor and embodied in solid state ICs.
 83. TheEOAMT of claim 70, further comprising visual status indicators,preferably in form of one or more LEDs which are driven by themicroprocessor to indicate when a predefined one of the tool status ispresent or absent, including when the magnetic flux source is on or off,when the magnetic flux source is on and proximity of target is detectedby the first magnetic field sensors, when the tool's workpieceengagement surfaces contact the workpiece outside intended specificareas on target and when tool engagement with the workpiece is withinthreshold limits, showing a safe magnetic coupling state.
 84. An end ofarm magnetic coupling tool (EOAMT) devised for magnetically securing aferromagnetic work piece to a working face of the tool, comprising: i)an on-off switchable di-pole magnetic flux source; ii) a first housingcomponent in which is received the magnetic flux source; iii) a pair ofmagnetic pole extension shoes having each a work piece engagementsurface, wherein the pole extension shoes are mounted to the firsthousing component such as to receive magnetic flux from the magneticflux source and make such available at the work piece engagementsurfaces; iv) at least one, but preferably a number of first magneticfield detection sensors equal in number to the pole extension shoes,located a predetermined distance away but in close proximity to a fluxdetection surface preferably at an end opposite the work pieceengagement surface of an associated one of the pole extension shoes; v)a pair of degaussing electrical windings, one each wound about a sectionof an associated one of the two magnetic pole extension shoes; and vi) alogic control circuit operative to (i) receive an output signal from theat least one magnetic field detection sensor and determine from saidoutput signal(s) an operating state of the tool indicative of themagnetic flux source being switched off, (ii) switch-on an electricpower supply to the degaussing electrical windings after detection of anoff state of the magnetic flux source and (iii) perform a degaussingcycle wherein the degaussing electrical windings generate an oscillatingand alternating magnetic field over a predetermined time.
 85. The EOAMTof claim 84, wherein the first magnetic field sensors and the logiccontrol circuit are housed within a second housing component which ispreferably of multi-piece construction and which is secured to the firsthousing component such as to provide a compact-footprint EOAMT withintegrated work piece coupling, magnetic field detection, workpiece-tool interface detection and degaussing functionalities. 86-101.(canceled)